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