Score : 100 points
There are N children in AtCoder Kindergarten. Mr. Evi will arrange the children in a line, then give 1 candy to the first child in the line, 2 candies to the second child, ..., N candies to the N-th child. How many candies will be necessary in total?
The input is given from Standard Input in the following format:
N
Print the necessary number of candies in total.
3
6
The answer is 1+2+3=6.
10
55
The sum of the integers from 1 to 10 is 55.
1
1
Only one child. The answer is 1 in this case.