child_num = eval(input())

child_num = int(child_num)

candy_num = int((child_num**2 + child_num) / 2)

print(candy_num)
#子供の数を入力

child_num = int(eval(input()))



candy_num = int((child_num**2 + child_num) / 2)

print(candy_num)
child_num = eval(input())
child_num = int(child_num)
candy_num = int((child_num**2 + child_num) / 2)
print(candy_num)

# 子供の数を入力
child_num = int(eval(input()))
candy_num = int((child_num**2 + child_num) / 2)
print(candy_num)

-child_num = eval(input()) -child_num = int(child_num) +# 子供の数を入力 +child_num = int(eval(input()))