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.
s=set()

def f(x,y,z):
        s.add(z)
        x_=x+z*10
        y_=y+z*10
        if x_<=n and x_!=0: f(x,y,x_)
        if y_<=n and y_!=0: f(x,y,y_)

n=int(input())
for i in range(1,10):
    for j in range(0,10):
        f(i,j,0)
        
print(len(s)-1)
