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 itertools import product
n = int(input().strip())
if n<102:
    print(n)
else:
    res = set()
    combination = (str(i)+str(j) for i in range(10) for j in range(i+1,10))
    for it in (product(comb,repeat=l) for comb in combination for l in range(1,len(str(n))+1)):
        for line in it:
            tmp = int("".join(line))
            if tmp and tmp<=n:
                res.add(tmp)
    print(len(res))
 	  			  	  	  	 				  	  			