n = int(eval(input()))

ans = 0

for i in range(1,n+1):

    ans += i

print(ans)
def main():

    N = int(eval(input()))

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





if __name__ == '__main__':

    main()

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

def main():
    N = int(eval(input()))
    print((N * (N + 1) // 2))


if __name__ == "__main__":
    main()

-n = int(eval(input())) -ans = 0 -for i in range(1, n + 1): -    ans += i -print(ans) +def main(): +    N = int(eval(input())) +    print((N * (N + 1) // 2)) + + +if __name__ == "__main__": +    main()