Count Good Strings

You are given two non-negative integers \(a\) and \(b\). A good string is defined as a string containing only the characters 'a' and 'b', with all occurrences of 'a' appearing before any 'b'.

The total number of such strings is given by the binomial coefficient:

\(\binom{a+b}{a}\)

For example, if \(a = 2\) and \(b = 3\), then there are \(\binom{5}{2} = 10\) different good strings.

Your task is to compute and output the number of good strings that can be constructed with exactly \(a\) 'a's and \(b\) 'b's.

inputFormat

A single line containing two space-separated non-negative integers (a) and (b).

outputFormat

Output a single integer — the number of distinct good strings that can be formed.## sample

2 3

10