Polycarpus loves lucky numbers. Everybody knows that lucky numbers are positive integers, whose decimal representation (without leading zeroes) contain only the lucky digits *x* and *y*. For example, if *x* = 4, and *y* = 7, then numbers 47, 744, 4 are lucky.

Let's call a positive integer *a* undoubtedly lucky, if there are such digits *x* and *y* (0 ≤ *x*, *y* ≤ 9), that the decimal representation of number *a* (without leading zeroes) contains only digits *x* and *y*.

Polycarpus has integer *n*. He wants to know how many positive integers that do not exceed *n*, are undoubtedly lucky. Help him, count this number.
The first line contains a single integer *n* (1 ≤ *n* ≤ 10<sup class="upper-index">9</sup>) — Polycarpus's number.
# 467 Fedor and game
'''
n,m,k = map(int,input().split())
array = []
for i in range(m+1):
	j = input()
	array.append(j)

cout = 0
for i in range(m):
	Xor = bin(int(array[i])^int(array[-1]))[2:]
	if Xor.count('1') <= k:
		cout += 1
print(cout)
'''
array = []
for x in range(0,10):
        for y in range(0,10):
                for i in range(0,10):
                        for j in range(0,2**i):
                                b = bin(j)[2:]
                                b = b.zfill(i)
                                b = b.replace("0",str(x))
                                b = b.replace("1",str(y))
                                array.append(int(b))
cout = 0
array = set(array)
a = int(input())
for k in array:
        if int(k) <= a:
                cout += 1
if a == 10**9:
        print(cout)
else:
        print(cout-1)
