n = int(input())
c = 0
for i in range(10, n + 1):
    s = i // 10 % 10
    g = i // 1 % 10
    if s == 0 or g == 0:
        c += 1
print(c)

/**************************************************************
	Problem: 1750
	User: admin
	Language: Python
	Result: Accepted
	Time:122 ms
	Memory:34244 kb
****************************************************************/