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?

x = int(input())

print(x*(x+1)/2)

x = int(input())

print(int(x*(x+1)/2))