CF244B Undoubtedly Lucky Numbers

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

The first line contains a single integer $ n $ $ (1

Print a single integer that says, how many positive integers that do not exceed $ n $ are undoubtedly lucky.

In the first test sample all numbers that do not exceed $ 10 $ are undoubtedly lucky. In the second sample numbers 102, 103, 104, 105, 106, 107, 108, 109, 120, 123 are not undoubtedly lucky.