Tsort problem-NZEC error

general
,
1

The OJ displays NZEC can anyone help me

import java.io.*;
import java.util.*;
 
public class Test {
	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	public static void main(String[] args) throws IOException {
		
		int array[]   = new int[10001];
		int pointer[] = {10002,-1};
		int tc = Integer.parseInt(br.readLine());
		
		for(int i=1;i<=tc;i++){
			int n = Integer.parseInt(br.readLine());
			array[n]++;
			
			pointer[0] = pointer[0] > n ? n : pointer[0];
			pointer[1] = pointer[1] < n ? n : pointer[1];
		}
		StringBuilder b = new StringBuilder("");
		for(int j=pointer[0];j<=pointer[1];j++){
			for(int i=0;i<array[j];i++){
				System.out.print(j);
			}
		}
	}
}