///sume partiale
#include <bits/stdc++.h>
#define N 101
using namespace std;
int a[N],n;
long long s[N];
int main()
{
   int i,st,dr;
   cin>>n;
   s[0]=0;
   for(i=1;i<=n;i++)
   {
       cin>>a[i];
       s[i]=s[i-1]+a[i]; ///vector de sume partiale
   }
   cin>>st>>dr;
   cout<<s[dr]-s[st-1];

    return 0;
}
/*
8
12 10 15 7 17 13 19 14
2 4
*/