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.
#d=sorted(d,key=lambda x:(len(d[x]),-x))  d=dictionary     d={x:set() for x in arr}
#n=int(input())
#n,m,k= map(int, input().split())
import heapq
#for _ in range(int(input())):
#n,k=map(int, input().split())
#input=sys.stdin.buffer.readline
#for _ in range(int(input())):
def dfs(x):
    if 0< x <=n :
        s.add(x)
        x*=10
        dfs(x+i)
        dfs(x+j)

n=int(input())
#arr = list(map(int, input().split()))
s=set()

for i in range(1,10):
    for j in range(10):
        dfs(i)
print(len(s))
