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.
def bepi(n):
    lst=[0]*(10000)
    dc={}
    i=0
    ans=0
    while(i<10):
        j=i+1
        while(j<10):
            a=0
            b=0
            if i!=0 and i<=n:
                lst[a]=i
                a+=1
            if j!=0 and j<=n:
                lst[a]=j
                a+=1
            while(b<a):
                tmp=lst[b]
                if (tmp*10)+i<=n:
                    lst[a]=(tmp*10)+i
                    a+=1
                if (tmp*10)+j<=n:
                    lst[a]=(tmp*10)+j
                    a+=1
                b+=1
            b=0
            while(b<a):
                if not lst[b] in dc:
                    ans+=1
                    dc[lst[b]]=1
                b+=1
            j+=1
        i+=1
    return ans


n=int(input())
print(bepi(n))
