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.
A = []
for i in range(2**10):
    LIST1 = bin(i)[2:]
    A.append(LIST1)
LIST2 = []
for bin in A:
    for i in range(10):
        for j in range(10):
            LIST1 = bin
            LIST1 = LIST1.replace("0", "#")
            LIST1 = LIST1.replace("1", str(j))
            LIST1 = LIST1.replace("#", str(i))
            LIST2.append(int(LIST1))
LIST2 = list(set(LIST2))
LIST2.sort()
n = int(input())
for i in range(1, len(LIST2)):
    if(LIST2[i] > n):
        print(i - 1)
        break

