Why test cases failing?

find the maximum difference between any two element in an array.
if an element is arr[i] and another element is arr[j] then difference will be |arr[i]-arr[j]| .

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


public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n;
        n = sc.nextInt();
        int []arr=new int[n];
        for(int i=0;i<n;++i){
                arr[i]=sc.nextInt();
        }
        ArrayProblem(arr);  
    }

    
    public static void ArrayProblem(int []arr) {
         int n = arr.length;

        int max = arr[0]- arr[1];
       
        for (int i = 0; i<n; i++)
        {
            for (int j = i; j<n; j++)
            {
                if (arr[j] - arr[i] > max)
                    max = arr[j] - arr[i];
            }
        }
       System.out.print(max);
    }
}