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.
import math

def ncr(n,r):
    f = math.factorial
    return f(n) // f(r) // f(n-r)

n = int(input())
c = len(str(n))
count=0
for i in range(1,10):
	for j in range(1,c):
		count+=1

for i in range(1,10):
	for j in range(10):
		if i!=j:
			for k in range(1,c-1):
				for l in range(1,k+1):
					count += ncr(k, l)

s=str(n)[0]
for i in range(c-1):
	s = s+'0'

for i in range(int(s),n+1):
	s = set(str(i))
	if len(s)<=2:
		count+=1;

print(count)