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.
from random import randint


n = int(input())
ses = set()
for c1 in range(10):
    for c2 in range(c1 + 1, 10):
        C = [c1, c2]
        for _ in range(1000):
            kek = C[randint(0, 1)]
            while kek <= n:
                ses.add(kek)
                kek *= 10; kek += C[randint(0, 1)]
print(len(ses)-1)