n = int(input())
sum = 0
i = 1
for i in range(n):
    sum = sum + i
print(sum)

2f63b20c5cf18f9042b9999be41000e7853f7469
<mask token>

<mask token>
for i in range(n):
    sum = sum + i
print(sum)

n = int(input())
sum = 0
i = 1
for i in range(n):
    sum = sum + i
print(sum)
