One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of *n* different natural numbers from 1 to *n* to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.
Input data contains the only number *n* (1 ≤ *n* ≤ 10<sup class="upper-index">9</sup>).
For *n* = 10 the answer includes numbers 1 and 10.
10
2
20
3
72
3
99
3
100
4
101
5
102
5
111
7
112
7
745
7
23536
31
1
1
1010011
83
312410141
511
1000000000
512
999999999
511
111111111
511
101010101
341
121212121
511
106341103
383
901556123
511
832513432
511
3
1
732875234
511
7
1
9
1
2
1
11
3
12
3
13
3
101020101
351
111100100
484
110110101
437
100111001
313
100100
36
110100102
421
x=[1, 10, 11, 100, 101, 110, 111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111, 10000, 10001, 10010, 10011, 10100, 10101, 10110, 10111, 11000, 11001, 11010, 11011, 11100, 11101, 11110, 11111, 100000, 100001, 100010, 100011, 100100, 100101, 100110, 100111, 101000, 101001, 101010, 101011, 101100, 101101, 101110, 101111, 110000, 110001, 110010, 110011, 110100, 110101, 110110, 110111, 111000, 111001, 111010, 111011, 111100, 111101, 111110, 111111, 1000000, 1000001, 1000010, 1000011, 1000100, 1000101, 1000110, 1000111, 1001000, 1001001, 1001010, 1001011, 1001100, 1001101, 1001110, 1001111, 1010000, 1010001, 1010010, 1010011, 1010100, 1010101, 1010110, 1010111, 1011000, 1011001, 1011010, 1011011, 1011100, 1011101, 1011110, 1011111, 1100000, 1100001, 1100010, 1100011, 1100100, 1100101, 1100110, 1100111, 1101000, 1101001, 1101010, 1101011, 1101100, 1101101, 1101110, 1101111, 1110000, 1110001, 1110010, 1110011, 1110100, 1110101, 1110110, 1110111, 1111000, 1111001, 1111010, 1111011, 1111100, 1111101, 1111110, 1111111,10000000, 10000001, 10000010, 10000011, 10000100, 10000101, 10000110, 10000111, 10001000, 10001001, 10001010, 10001011, 10001100, 10001101, 10001110, 10001111, 10010000, 10010001, 10010010, 10010011, 10010100, 10010101, 10010110, 10010111, 10011000, 10011001, 10011010, 10011011, 10011100, 10011101, 10011110, 10011111, 10100000, 10100001, 10100010, 10100011, 10100100, 10100101, 10100110, 10100111, 10101000, 10101001, 10101010, 10101011, 10101100, 10101101, 10101110, 10101111, 10110000, 10110001, 10110010, 10110011, 10110100, 10110101, 10110110, 10110111, 10111000, 10111001, 10111010, 10111011, 10111100, 10111101, 10111110, 10111111, 11000000, 11000001, 11000010, 11000011, 11000100, 11000101, 11000110, 11000111, 11001000, 11001001, 11001010, 11001011, 11001100, 11001101, 11001110, 11001111, 11010000, 11010001, 11010010, 11010011, 11010100, 11010101, 11010110, 11010111, 11011000, 11011001, 11011010, 11011011, 11011100, 11011101, 11011110, 11011111, 11100000, 11100001, 11100010, 11100011, 11100100, 11100101, 11100110, 11100111, 11101000, 11101001, 11101010, 11101011, 11101100, 11101101, 11101110, 11101111, 11110000, 11110001, 11110010, 11110011, 11110100, 11110101, 11110110, 11110111, 11111000, 11111001, 11111010, 11111011, 11111100, 11111101, 11111110, 11111111, 100000000, 100000001, 100000010, 100000011, 100000100, 100000101, 100000110, 100000111, 100001000, 100001001, 100001010, 100001011, 100001100, 100001101, 100001110, 100001111, 100010000, 100010001, 100010010, 100010011, 100010100, 100010101, 100010110, 100010111, 100011000, 100011001, 100011010, 100011011, 100011100, 100011101, 100011110, 100011111, 100100000, 100100001, 100100010, 100100011, 100100100, 100100101, 100100110, 100100111, 100101000, 100101001, 100101010, 100101011, 100101100, 100101101, 100101110, 100101111, 100110000, 100110001, 100110010, 100110011, 100110100, 100110101, 100110110, 100110111, 100111000, 100111001, 100111010, 100111011, 100111100, 100111101, 100111110, 100111111, 101000000, 101000001, 101000010, 101000011, 101000100, 101000101, 101000110, 101000111, 101001000, 101001001, 101001010, 101001011, 101001100, 101001101, 101001110, 101001111, 101010000, 101010001, 101010010, 101010011, 101010100, 101010101, 101010110, 101010111, 101011000, 101011001, 101011010, 101011011, 101011100, 101011101, 101011110, 101011111, 101100000, 101100001, 101100010, 101100011, 101100100, 101100101, 101100110, 101100111, 101101000, 101101001, 101101010, 101101011, 101101100, 101101101, 101101110, 101101111, 101110000, 101110001, 101110010, 101110011, 101110100, 101110101, 101110110, 101110111, 101111000, 101111001, 101111010, 101111011, 101111100, 101111101, 101111110, 101111111, 110000000, 110000001, 110000010, 110000011, 110000100, 110000101, 110000110, 110000111, 110001000, 110001001, 110001010, 110001011, 110001100, 110001101, 110001110, 110001111, 110010000, 110010001, 110010010, 110010011, 110010100, 110010101, 110010110, 110010111, 110011000, 110011001, 110011010, 110011011, 110011100, 110011101, 110011110, 110011111, 110100000, 110100001, 110100010, 110100011, 110100100, 110100101, 110100110, 110100111, 110101000, 110101001, 110101010, 110101011, 110101100, 110101101, 110101110, 110101111, 110110000, 110110001, 110110010, 110110011, 110110100, 110110101, 110110110, 110110111, 110111000, 110111001, 110111010, 110111011, 110111100, 110111101, 110111110, 110111111, 111000000, 111000001, 111000010, 111000011, 111000100, 111000101, 111000110, 111000111, 111001000, 111001001, 111001010, 111001011, 111001100, 111001101, 111001110, 111001111, 111010000, 111010001, 111010010, 111010011, 111010100, 111010101, 111010110, 111010111, 111011000, 111011001, 111011010, 111011011, 111011100, 111011101, 111011110, 111011111, 111100000, 111100001, 111100010, 111100011, 111100100, 111100101, 111100110, 111100111, 111101000, 111101001, 111101010, 111101011, 111101100, 111101101, 111101110, 111101111, 111110000, 111110001, 111110010, 111110011, 111110100, 111110101, 111110110, 111110111, 111111000, 111111001, 111111010, 111111011, 111111100, 111111101, 111111110,111111111,1000000000, 1000000001, 1000000010, 1000000011, 1000000100, 1000000101, 1000000110, 1000000111, 1000001000, 1000001001, 1000001010, 1000001011, 1000001100, 1000001101, 1000001110, 1000001111, 1000010000, 1000010001, 1000010010, 1000010011, 1000010100, 1000010101, 1000010110, 1000010111, 1000011000, 1000011001, 1000011010, 1000011011, 1000011100, 1000011101, 1000011110, 1000011111, 1000100000, 1000100001, 1000100010, 1000100011, 1000100100, 1000100101, 1000100110, 1000100111, 1000101000, 1000101001, 1000101010, 1000101011, 1000101100, 1000101101, 1000101110, 1000101111, 1000110000, 1000110001, 1000110010, 1000110011, 1000110100, 1000110101, 1000110110, 1000110111, 1000111000, 1000111001, 1000111010, 1000111011, 1000111100, 1000111101, 1000111110, 1000111111, 1001000000, 1001000001, 1001000010, 1001000011, 1001000100, 1001000101, 1001000110, 1001000111, 1001001000, 1001001001, 1001001010, 1001001011, 1001001100, 1001001101, 1001001110, 1001001111, 1001010000, 1001010001, 1001010010, 1001010011, 1001010100, 1001010101, 1001010110, 1001010111, 1001011000, 1001011001, 1001011010, 1001011011, 1001011100, 1001011101, 1001011110, 1001011111, 1001100000, 1001100001, 1001100010, 1001100011, 1001100100, 1001100101, 1001100110, 1001100111, 1001101000, 1001101001, 1001101010, 1001101011, 1001101100, 1001101101, 1001101110, 1001101111, 1001110000, 1001110001, 1001110010, 1001110011, 1001110100, 1001110101, 1001110110, 1001110111, 1001111000, 1001111001, 1001111010, 1001111011, 1001111100, 1001111101, 1001111110, 1001111111, 1010000000, 1010000001, 1010000010, 1010000011, 1010000100, 1010000101, 1010000110, 1010000111, 1010001000, 1010001001, 1010001010, 1010001011, 1010001100, 1010001101, 1010001110, 1010001111, 1010010000, 1010010001, 1010010010, 1010010011, 1010010100, 1010010101, 1010010110, 1010010111, 1010011000, 1010011001, 1010011010, 1010011011, 1010011100, 1010011101, 1010011110, 1010011111, 1010100000, 1010100001, 1010100010, 1010100011, 1010100100, 1010100101, 1010100110, 1010100111, 1010101000, 1010101001, 1010101010, 1010101011, 1010101100, 1010101101, 1010101110, 1010101111, 1010110000, 1010110001, 1010110010, 1010110011, 1010110100, 1010110101, 1010110110, 1010110111, 1010111000, 1010111001, 1010111010, 1010111011, 1010111100, 1010111101, 1010111110, 1010111111, 1011000000, 1011000001, 1011000010, 1011000011, 1011000100, 1011000101, 1011000110, 1011000111, 1011001000, 1011001001, 1011001010, 1011001011, 1011001100, 1011001101, 1011001110, 1011001111, 1011010000, 1011010001, 1011010010, 1011010011, 1011010100, 1011010101, 1011010110, 1011010111, 1011011000, 1011011001, 1011011010, 1011011011, 1011011100, 1011011101, 1011011110, 1011011111, 1011100000, 1011100001, 1011100010, 1011100011, 1011100100, 1011100101, 1011100110, 1011100111, 1011101000, 1011101001, 1011101010, 1011101011, 1011101100, 1011101101, 1011101110, 1011101111, 1011110000, 1011110001, 1011110010, 1011110011, 1011110100, 1011110101, 1011110110, 1011110111, 1011111000, 1011111001, 1011111010, 1011111011, 1011111100, 1011111101, 1011111110, 1011111111, 1100000000, 1100000001, 1100000010, 1100000011, 1100000100, 1100000101, 1100000110, 1100000111, 1100001000, 1100001001, 1100001010, 1100001011, 1100001100, 1100001101, 1100001110, 1100001111, 1100010000, 1100010001, 1100010010, 1100010011, 1100010100, 1100010101, 1100010110, 1100010111, 1100011000, 1100011001, 1100011010, 1100011011, 1100011100, 1100011101, 1100011110, 1100011111, 1100100000, 1100100001, 1100100010, 1100100011, 1100100100, 1100100101, 1100100110, 1100100111, 1100101000, 1100101001, 1100101010, 1100101011, 1100101100, 1100101101, 1100101110, 1100101111, 1100110000, 1100110001, 1100110010, 1100110011, 1100110100, 1100110101, 1100110110, 1100110111, 1100111000, 1100111001, 1100111010, 1100111011, 1100111100, 1100111101, 1100111110, 1100111111, 1101000000, 1101000001, 1101000010, 1101000011, 1101000100, 1101000101, 1101000110, 1101000111, 1101001000, 1101001001, 1101001010, 1101001011, 1101001100, 1101001101, 1101001110, 1101001111, 1101010000, 1101010001, 1101010010, 1101010011, 1101010100, 1101010101, 1101010110, 1101010111, 1101011000, 1101011001, 1101011010, 1101011011, 1101011100, 1101011101, 1101011110, 1101011111, 1101100000, 1101100001, 1101100010, 1101100011, 1101100100, 1101100101, 1101100110, 1101100111, 1101101000, 1101101001, 1101101010, 1101101011, 1101101100, 1101101101, 1101101110, 1101101111, 1101110000, 1101110001, 1101110010, 1101110011, 1101110100, 1101110101, 1101110110, 1101110111, 1101111000, 1101111001, 1101111010, 1101111011, 1101111100, 1101111101, 1101111110, 1101111111, 1110000000, 1110000001, 1110000010, 1110000011, 1110000100, 1110000101, 1110000110, 1110000111, 1110001000, 1110001001, 1110001010, 1110001011, 1110001100, 1110001101, 1110001110, 1110001111, 1110010000, 1110010001, 1110010010, 1110010011, 1110010100, 1110010101, 1110010110, 1110010111, 1110011000, 1110011001, 1110011010, 1110011011, 1110011100, 1110011101, 1110011110, 1110011111, 1110100000, 1110100001, 1110100010, 1110100011, 1110100100, 1110100101, 1110100110, 1110100111, 1110101000, 1110101001, 1110101010, 1110101011, 1110101100, 1110101101, 1110101110, 1110101111, 1110110000, 1110110001, 1110110010, 1110110011, 1110110100, 1110110101, 1110110110, 1110110111, 1110111000, 1110111001, 1110111010, 1110111011, 1110111100, 1110111101, 1110111110, 1110111111, 1111000000, 1111000001, 1111000010, 1111000011, 1111000100, 1111000101, 1111000110, 1111000111, 1111001000, 1111001001, 1111001010, 1111001011, 1111001100, 1111001101, 1111001110, 1111001111, 1111010000, 1111010001, 1111010010, 1111010011, 1111010100, 1111010101, 1111010110, 1111010111, 1111011000, 1111011001, 1111011010, 1111011011, 1111011100, 1111011101, 1111011110, 1111011111, 1111100000, 1111100001, 1111100010, 1111100011, 1111100100, 1111100101, 1111100110, 1111100111, 1111101000, 1111101001, 1111101010, 1111101011, 1111101100, 1111101101, 1111101110, 1111101111, 1111110000, 1111110001, 1111110010, 1111110011, 1111110100, 1111110101, 1111110110, 1111110111, 1111111000, 1111111001, 1111111010, 1111111011, 1111111100, 1111111101, 1111111110, 1111111111];n=int(input())
for i in range(len(x)):
    if n<x[i]: print(len(x[0:i]));break