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.
a=int(input())
l=[]
for i in range(10):
    for j in range(10):
        for k in range(8):
            c=bin(k)[2:]
            d=c
            c=c.replace('0',str(j))
            c=c.replace('1',str(i))
            d=d.replace('1',str(j))
            d=d.replace('0',str(i))
            l.append(int(d))
            l.append(int(c))
l=list(set(l))
l.sort()
l.pop(0)
s=0
for z in l:
    if z <= a:
        s+=1
    else:
        print(s) 
        break



