Strange Multiplication

Time Limit: 1 sec

 

The Problem

Shawon is a student of Programming School and Mr. Nezam is teacher of this school. Shawon allways multiply two number in strange way which is not a right way. This multiplication did not understand Mr. Nezam. Can you help Mr. Nezam to find the strange multiplication result. The strange multiplication are...

 

2 x 3 = 1

3 x 4 = 5

4 x 5 =11

...

...

...

M x N = ?

 

Your task is to find the strange multiplication result of two integer numbers M and N.

 

 

The Input

The input file contains 2 integer numbers M, and N (1<M < 1000, 1<N<1000).

 

The Output

Output will show the strange multiplication result in a separate line.

 

Sample Input

 3 4

 

Sample Output

 5

 

 

 

 

Problem Setter: Shahin ShamS