Найти сумму ряда s = 15 + 16 + 17 + + n.

С++
#include<iostream>
using namespace std;
main()
{
int a, s;
cin >> a;
for(int i = 15; i <= a; i++)
s += i;
cout << s;
}
Python
a = int(input())
s = 0
for i in range(15, a + 1):
    s += i
print(s)
Pascal
var a, s, i: integer;
begin
read(a);
for i := 15 to a do s += i;
write(s);
end.