Problems
Simple Question
Simple Question
Given integer $n$, you must calculate the sum of all integers between $1$ and $n$ (including $1$ and $n$).
\InputFile
Each line has one integer $n~(|n| \le 10000)$. The last line contains $0$ and is not processed.
\OutputFile
For each value of $n$ print the answer on a separate line.
Input example #1
1 10 0
Output example #1
1 55