Problem Description

Compute the value of $1+2+3+\cdots+(n-1)+n$, where the positive integer $n$ is no more than 100. Since you are not as smart as Gauss, you are not allowed to use the arithmetic sequence sum formula to get the answer directly.

Input Format

Input a positive integer $n$.

Output Format

Output a positive integer representing the final sum.

100

5050

Hint

Constraints: $1 \leq n \leq 100$.

Translated by ChatGPT 5