Army

军队晋升年数计算

最新推荐文章于 2022-11-12 01:18:59 发布

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本文介绍了一种计算军队中士兵晋升所需年数的方法，通过输入士兵当前和目标军衔等级，程序将输出达到目标军衔所需的年份数。具体实现通过输入年份数量、各军衔晋升年数、当前军衔和目标军衔来完成。

Description

The Berland Armed Forces System consists of n ranks that are numbered using natural numbers from 1 to n, where 1 is the lowest rank and n is the highest rank.

One needs exactly d_i years to rise from rank i to rank i + 1. Reaching a certain rank i having not reached all the previous i - 1 ranks is impossible.

Vasya has just reached a new rank of a, but he dreams of holding the rank of b. Find for how many more years Vasya should serve in the army until he can finally realize his dream.

Input

The first input line contains an integer n (2 ≤ n ≤ 100). The second line contains n - 1 integers d_i (1 ≤ d_i ≤ 100). The third input line contains two integers a and b (1 ≤ a < b ≤ n). The numbers on the lines are space-separated.

Output

Print the single number which is the number of years that Vasya needs to rise from rank a to rank b.

Sample Input

Input

3
5 6
1 2

Output

Input

3
5 6
1 3

Output

#include<cstdio>
#include<iostream>
using namespace std;

int main(){
    int n,i,a,b,num[110],sum;
    while(cin>>n){
        sum=0;
        for(i=2;i<=n;i++){
            cin>>num[i];
        }
        cin>>a>>b;
        for(i=a+1;i<=b;i++){
            sum+=num[i];
        }
        cout<<sum<<endl;
    }
    return 0;
}