In kindergarten Sweetheart
N children. Anna Nikolaevna lines up the children, then distributes 1 candy to the first child, 2 candies to the second child, ...,
N candies to the
N-th child. How many sweets will Anna Nikolaevna need in total?
Input
The input is an integer
N (
\(1 <= N <=100\)).
Imprint
Display the answer to the problem.
Examples