//	Use loop to comput -
//		Sum(N) = N + (N-1) + ... 2 + 1
//	Add a loop, 0 to quit

#include <iostream>

using namespace std;

// loop function for sum
int f(int n)
{
	int s=0;
	for(int i=1; i<=n; i++)
		s += i;	// 1 + 2 + .. n
	return s;
}

int main()
{	int N;

	cout << "Max: " << INT_MAX << "\n\n";

	cout << "input N for computing N! - ";
	cin >> N;
	while( N != 0 )
	{
		cout << "Sum(N) = " << f(N) << "\n\n";
		cout << "input N for computing Sum(N) (0 to quit): ";
		cin >> N;
	}
	return 0;
}