poj 2924

Description

Johann Carl Friedrich Gauß (1777 – 1855) was one of the most important German mathematicians. For those of you who remember the Deutsche Mark, a picture of him was printed on the 10 – DM bill. In elementary school, his teacher J. G. Büttner tried to occupy the pupils by making them add up the integers from 1 to 100. The young Gauß surprised everybody by producing the correct answers (5050) within seconds.

Can you write a computer program that can compute such sums really quickly?

Given two integers n and m, you should compute the sum of all the integers from n to m. In other words, you should compute

Input

The first line contains the number of scenarios. Each scenario consists of a line containing the numbers n and m (−10⁹ ≤ n ≤ m ≤ 10⁹).

Output

The output for every scenario begins with a line containing “Scenario #i:”, where i is the number of the scenario starting at 1. Then print the sum of all integers from n to m. Terminate the output for the scenario with a blank line.

Sample Input

3
1 100
-11 10
-89173 938749341

Sample Output

Scenario #1:
5050

Scenario #2:
-11

Scenario #3:
440625159107385260

#include<iostream>
using namespace std;
int main()
{
    int n , count = 1;
    __int64 x , y, temp;
    __int64 sum;
    cin>>n;
    temp = n;
    while(temp--)
    {
        sum = 0;
        scanf("%I64d%I64d" , &x , &y);
        sum = (x+y)*(y-x+1)/2;
        cout<<"Scenario #"<<count<<':'<<endl;
        printf("%I64d\n" , sum);
        if(count!=n) cout<<endl;
        count++;
    }
    return 0;
}