C Programing Language

Sub - Rectangle

As a lot of students dont like long problem statements, Lili decided to make this one as short as possible. She asks you to solve a simple problem: given a rectangle of size N M, determine how many sub-rectangles are there in the rectangle!

Format Input

The only line of input consists of two integers N and M, the dimension of the given rectangle.

Format Output

Output a single integer X which is the amount of sub-rectangles in the given rectangle.

Constraints

1 N 50

1 M 50

Sample Input (standard input)

2 3

Sample Output (standard output)

18

Explanation

On the sample, there are 18 sub-rectangles :

6 of 1 1 rectangles

4 of 1 2 rectangles

2 of 1 3 rectangles

3 of 2 1 rectangles

NOTE :

Input And Output Must Be The Same

Don't use library Stdlib.h