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.
#!/usr/bin/python3.6
# -*- coding: utf-8 -*-
# @Time    : 2020/11/30 8:35 PM
# @Author  : Songtao Li


def is_lucky(x: int):
    item = set()
    while x:
        i = x % 10
        x = x // 10
        item.add(i)

        if len(item) > 2:
            return False
    return True


if __name__ == "__main__":
    n = int(input())
    if n <= 100:
        print(n)
    else:
        count = 100
        for i in range(101, n + 1):

            if is_lucky(i):
                count += 1
        print(count)

	 		     		 		  				  		    	