if语句

#include<iostream>
using namespace std;

int main()
{
	cout <<"Enter two numbers:"<<endl;
	int v1,v2;
	cin>> v1 >> v2;
	int lower,upper;
	if(v1 <= v2)
	{
		lower = v1;
		upper = v2;
	}
	else
	{
		lower = v2;
		upper = v1;
	}

	int sum = 0;
	for(int val = 1; val <= upper; ++val)
	{
		sum += val;
	}
	cout <<"sum of "<<lower<<" to "<<upper <<" inclusive is "<<sum <<endl;
	return 0;
}