my code:

import java.util.ArrayList; import java.util.Scanner;

public class Solution { public static void main(String[] args) { Scanner scan = new Scanner(System.in);

    ArrayList<ArrayList<Integer>> ml = new ArrayList<>();

    int n = scan.nextInt();      
    for (int i = 0; i < n; i++) {
        int x = scan.nextInt();
        ArrayList<Integer> list = new ArrayList<>();
        for (int j = 0; j < x; j++) {
            int z = scan.nextInt();
            list.add(z);
        }
        ml.add(list);
    }

    int m = scan.nextInt();
    for(int i=0; i<m; i++){
        int a= scan.nextInt();
        int b= scan.nextInt();
        try{
            System.out.println(ml.get(a-1).get(b-1));
        }
        catch(IndexOutOfBoundsException e){
            System.out.println("ERROR!");
        }
    }

    scan.close();
}

}