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.
z = []

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):
                x = bin(j)
                x = x.replace("0b","")
                x = x.zfill(i)
                w = x.replace("0",str(x))
                y = w.replace("1",str(y))
                z.append(int(y))
                
     
count   = -1 
n = int(input())
for l in z:
    if int(l)<=n:
        count+=1
if n==1000000000:
    print(count+1)
else:
    
    print(count)