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.
list1 = []
for x in range(0,10):
    for y in range(x+1,10):
        for l in range(1,1024):
            s = bin(l)[2:]
            imp = s
            s = s.replace('1',str(y))
            s = s.replace('0',str(x))
            list1.append(int(s))
            imp = imp.replace('0',str(y))
            imp = imp.replace('1',str(x))
            list1.append(int(imp))
list1 = list(set(list1))
list1.sort()
list1.pop(0)
n = int(input())
c = 0
for i in list1:
    if i<=n:
        c+=1
print(c)