#include<iostream>
using namespace std;
int t[301];
int main()
{
    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;
    return 0;
}
/**************************************************************
	Problem: 2088
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:24 ms
	Memory:2076 kb
****************************************************************/