#include <bits/stdc++.h>
using namespace std;
int main(){
int t[301];
    int n;
    cin>>n;
    for (int i=1; i<=n; i++) cin>>t[i];
    int a,b,sum=0;
    cin>>a>>b;
    for (int i=a; i<=b; i++) sum+=t[i];
    cout<<sum<<endl;
}
/**************************************************************
	Problem: 2088
	User: yangjunwen
	Language: C++
	Result: Accepted
	Time:26 ms
	Memory:2072 kb
****************************************************************/