fjnu 1943 Gau? in Elementary School

Description

Johann Carl Friedrich Gau? (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. B?ttner tried to occupy the pupils by making them add up the integers from 1 to 100. The young Gau? 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

31 100-11 10-89173 938749341

Sample Output

Scenario #1:5050Scenario #2:-11Scenario #3:440625159107385260 

KEY:这题还好数据量不是很大，所以用_int64，给过了……（提交的时候要改成long long ）

Source:

#include<iostream>
using namespace std;

int main()
...{
//    freopen("fjnu_1943.in","r",stdin);
    long long a,b;
    int N;
    int i;
    long long j,sum=0;
    cin>>N;
    for(i=1;i<=N;i++)
    ...{
        scanf("%lld%lld",&a,&b);
        sum=(a+b)*(b-a+1)/2;
        cout<<"Scenario #"<<i<<":"<<endl;
        printf("%lld ",sum);
    }
    return 0;
}