N = int(eval(input()))

ans = 0

for i in range(N):

    ans += i + 1

print(ans)

import math

print((sum(list(range(1,int(eval(input()))+1)))))
N = int(eval(input()))
ans = 0
for i in range(N):
    ans += i + 1
print(ans)

import math

print((sum(list(range(1, int(eval(input())) + 1)))))

-N = int(eval(input())) -ans = 0 -for i in range(N): -    ans += i + 1 -print(ans) +import math + +print((sum(list(range(1, int(eval(input())) + 1)))))