/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception{
		Scanner sc = new Scanner(System.in);
		
		
		int n=sc.nextInt();
		int l=sc.nextInt();
		int r=sc.nextInt();
		int nums[] = new int[n];
		for(int i=0; i<n; i++){
			nums[i]=sc.nextInt();
		}
 
		int res = sumOfRange(l,r,nums);
		System.out.println(res);
	}
 
	public static int sumOfRange(int l,int r, int []nums){
		
		int p[] = new int[nums.length];
		p[0] = nums[0];
		for(int i=1;i<nums.length; i++){
			p[i] = p[i-1]+nums[i];
		}
		return p[r] - p[l-1];
 
	}
}