NATRANGE - Natural Number Sum

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Given two natural numbers, find the sum of the range of natural numbers.

Input

Input consists of two numbers a and b.

1 <= a <= b <= 10000

Output

Output a single integer n, the sum of all numbers from a to b.

Example

Input:
10 12

Output:
33

Explanation

10 + 11 + 12 = 33



Added by:Aswin Murugesh
Date:2014-12-28
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ASM64
Resource:Own Source