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.
lis=[]
for x in range(10):
    for y in range(10):
        for i in range(0,10):
            for j in range((2**i)+1):
                bn=(bin(j)[2:]).zfill(i)
            
                ans=''
                for k in bn:
                    if k=='0':
                        ans+=str(x)
                    else:
                        ans+=str(y)
                lis.append(int(ans))           
lis=((list(set(lis))))
a=int(input())
ans=0
for i in range(len(lis)):
    if lis[i]<=a and lis[i]!=0:
        ans+=1

print(ans)