Help me in solving DIVIDING problem

help
,
1

My issue

Why is my approach not working?

My code

/* package codechef; // 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 Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int a = (n*(n+1))/2;
		int sum=0;
		for(int i=0;i<n;i++){
		    sum+=sc.nextInt();
		}
		if(sum==a){
		    System.out.println("YES");
		}else{
		    System.out.println("NO");
		}
	}
}

Problem Link: Dividing Stamps Practice Coding Problem - CodeChef

2

@ashishprakashp
take long instead of int to avoid integer overflow.

3

Thank you!