Algorithm


A. Army
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

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 di 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 di (1 ≤ di ≤ 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.

Examples
input
Copy
3
5 6
1 2
output
Copy
5
input
Copy
3
5 6
1 3
output
Copy
11



 

Code Examples

#1 Code Example with C++ Programming

Code - C++ Programming

#include <cstdio>

int main(){
    int n; scanf("%d",&n);
    int *years = new int[n + 1];
    years[0] = years[1] = 0;
    int temp(0), currentRank(0), futureRank(0);
    for(int k = 2; k <= n; k++){scanf("%d", &temp); years[k] = years[k - 1] + temp;}
    scanf("%d %d", ¤tRank, &futureRank); 
    printf("%d", years[futureRank] - years[currentRank]);
    return 0;
}
Copy The Code & Try With Live Editor

Input

x
+
cmd
3
5 6
1 2

Output

x
+
cmd
5
Advertisements

Demonstration


Codeforces Solution-A. Army-Solution in C, C++, Java, Python

Previous
Codeforces solution 1080-B-B. Margarite and the best present codeforces solution
Next
CodeChef solution DETSCORE - Determine the Score CodeChef solution C,C+