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


public class seg_tree {

    public static class ss{ int s; int end;int index;ss(int s,int end,int index){this.s=s;this.end=end; this.index=index;} }

    public static int[] build(int[] v,int size)
    {
        int arr[]= new int[2*size];
        for(int i=0;i<size;i++)
        {
            arr[size+i]=v[i];
        }

        for(int i=size-1;i>=1;i--)
        {
            arr[i]=arr[2*i]+arr[2*i+1];
        }
        return(arr);
    }

    public static void range_query(int[] v,int size,int start,int end)
    {
        Stack<ss> stack= new Stack<ss>();
        stack.push(new ss(0,0,1));
        int sum=0;

        int s=0;
        int e=size-1;
        int mid=0;

        if(start<=s && end>=e){
            int val = (stack.pop()).index;
            sum=sum+v[val];
        }
        else if(start>e || end<s)
        {
            sum=-1;
        }

        else{
            int val = (stack.pop()).index;
            mid=(s+e)/2;
            stack.push(new ss(s,mid,2*val));
            stack.push(new ss(mid+1,e,(2*val)+1));
        }

        while(!stack.empty())
        {
            ss temp=(stack.pop());
            int val=(temp).index;s=temp.s;e=temp.end;

            if(start<=s && end>=e)
            {
                sum=sum+v[val];
            }
            else if (start>e || end<s) {
                sum=sum+0;
            }
            else
            {
                mid=(s+e)/2;
                stack.push(new ss(s,mid,2*val));
                stack.push(new ss(mid+1,e,(2*val)+1));
            }

        }

        System.out.println(sum);
    }


    public static int[] update(int[] v,int size,int index,int val)
    {
        int curr=v[size+index];
        int diff=val-curr;
        v[size+index]=val;
        int move=(size+index)/2;
        while(move>0)
        {
            v[move]=v[move]+diff;
            move=move/2;
        }

        return(v);
    }


    public static void prints(int[] arr,int size){
        for(int i=0;i<size;i++)
        {
            System.out.print(arr[i]+" ");
        }
        System.out.println();
    }
    public static void main(String[] args) throws java.lang.Exception {
        Scanner sc =new Scanner(System.in);
        // seg_tree st=new seg_tree();
        int[] v={2,3,5,6,7,9,10,11};
        int size=8;

        int[] tree=build(v,8);
        prints(tree,size*2);


        // tree=update(tree,size,2,2);
        // tree=update(tree,size,7,10);
        // prints(tree,size*2);
        range_query(tree,size,0,4);



    }

}