java Programm showing exception....this program works correctly but the I am not able to submit it in CodeChef

package com.company;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {
// write your code here
    int t;
    Scanner s=new Scanner(System.in);
    t=s.nextInt();
    int o[]=new int[t];
    for(int i=0;i<t;i++) {
        int n, k;
        int v, av, av1;
        n = s.nextInt();
        k = s.nextInt();
        v = s.nextInt();
        int a[] = new int[n];
        for (int j = 0; j < n; j++) {
            a[j] = s.nextInt();
        }
        int sum = 0;
        for (int j = 0; j < n; j++) {
            sum = sum + a[j];
        }

        o[i] = (v * (n + k) - sum) / k;
        boolean dec = (v * (n + k) - sum) % k == 0;
        if (o[i] < 1 || !dec) {
            o[i]=-1;
        }
    }
    for(int i =0;i<t;i++)
    System.out.println(o[i]);
}

}

Remove the package or put it within comments.
See this.

//