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.
n=int(input())

def bruteforce(number):
    res=0
    liste=[]
    while number>0:
        integer=number%10
        if integer not in liste:
            liste.append(integer)
        
        number=number//10
    return len(liste)<=2

answer=[0]

def dfs(num):
    if (num>0 and num<=n):
        answer[0]+=1
        for a in range(10):
            if bruteforce(num*10+a):
                dfs(num*10+a)

for chiffre in range(1,10):
    dfs(chiffre)

print(answer[0])