Help me in solving PREFPRO2 problem

help
,
1

My issue

hjg

My code

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

class Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
	Scanner sc=new Scanner(System.in);
	int n=sc.nextInt();
	int[] arr=new int[n+1];
	for(int i=1;i<=n;i++)
	{
	    arr[i]=sc.nextInt();
	}
	for(int i=2;i<=n;i++)
	{
	    arr[i]=arr[i]+arr[i-1];
	}
	int k=sc.nextInt();
	while(k-- >0)
	{
	    int a=sc.nextInt();
	      int b=sc.nextInt();
	      if(a == 0)
	      {
	        System.out.println(arr[b]);   
	      }
	     
	      else{
	          System.out.println(arr[b]-arr[a-1]); 
	      }
	      
	}

	}
}

Learning course: Prefix sums
Problem Link: Optimization Using Prefix Array Practice Problem in Prefix sums - CodeChef

2

@dilkhushkumar
use long instead of int