Getting java NZEC error on codechef compiler

Guys i am trying to solve the DAG Delete problem of December contest. My code runs perfectly fine on my computer and i have tested it for multiple cases. I have also made sure that everything is properly initialized and checked for corner cases too. Earlier i was using too much memory and even that is not the case now. Please tell me what are the not so common reasons where you people got Run Time Error or how should i proceed with debugging my code.

Best Regards

can you provide test cases for which you are getting error

I am facing the same problem in directing edges question. any suggestions?

i have tried to solve this package it’s working fine when i try it but when i upload the answer i get NZEC so plz someone help!
this is my code
java application1;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {

Scanner sc = new Scanner(;
int arr[][] = new int[100][2];

int x = sc.nextInt();
int y = sc.nextInt();

int ii = 0;
while ((x!=-1)&&(y!=-1)){
    arr[ii][0] = x;
    arr[ii][1] = y;
     x = sc.nextInt();
 y = sc.nextInt();

for (int i = 0; i < ii; i++) {

        x = arr[i][0];

        y = arr[i][1];
        if ((x == 1) || (y == 1)){

            System.out.println(x + "+" + y + "=" + (x + y));

System.out.println(x + “+” + y + " !=" + (x + y));