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Problems

Simple Question

Simple Question

Time limit 1 second
Memory limit 128 MiB

Given integer n, you must calculate the sum of all integers between 1 and n (including 1 and n).

Input data

Each line has one integer n~(|n| \le 10000). The last line contains 0 and is not processed.

Output data

For each value of n print the answer on a separate line.

Examples

Input example #1
1
10
0
Output example #1
1
55