자연수의 합

#include <iostream>
using namespace std;

int main(int argc, char** argv) {
	int i,a,b,sum = 0;
	
	cin >> a >> b;
	for(i =a; i<b;i++)
	{
		cout << i << " + ";
		sum+=i;
	}
	cout << i << " = " << sum+i;
	
	return 0;
}

---

3
7
3 + 4 + 5 + 6 + 7 = 25