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.
res = []

for x in range(0,10):
    for y in range(0,10):
        for i in range(0,10):
            for  j in range(0,2**i):
                b = bin(j)[2:]
                b = b.zfill(i)
                b = b.replace("0",str(x))
                b = b.replace("1",str(y))
                res.append(int(b))
                
     
count   = 0
res = set(res)
a = int(input())

for k in res:
    if int(k)<=a:
        count+=1
if a==10**9:
    print(count)
else:
    print(count-1)