#include <iostream>

using namespace std;

int main()
{
	int x, y, answer;

	cout << "Enter x = ";
	cin >> x;

	cout << "Enter y = ";
	cin >> y;

	answer = 0;

	while (x <= y)
	{
		answer = answer + x;
		x = x + 1;
	}

	cout << answer << endl;

	return 0;
}