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)

t = 1
while(t):
	n = int(input())
	if n<10:
		print(n)
		t-=1
		continue
	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'

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

	print(count)
	t-=1