코드 확인 부탁드립니다 ㅠ

import java.util.*;
  
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[][] arr = new int[n][n];
		for(int i = 0; i < n; i++) {
			for(int j = 0; j < n; j++) {
				arr[i][j] = sc.nextInt();
			}
		}
		int m = sc.nextInt();
		int[] moves = new int[m];
		for(int i = 0; i < m; i++){
			moves[i] = sc.nextInt();
		}
		
		ArrayList<Stack<Integer>> board = new ArrayList<>();
		for(int i = 0; i < n; i++) {
			Stack<Integer> temp = new Stack<>();
			for(int j = 0; j < n; j++) {
				if(arr[n-1-j][i] == 0) break;
				temp.push(arr[n-1-j][i]);
			}
			board.add(temp);
		}
		
		Stack<Integer> basket = new Stack<>();
		int result = 0;
		for(int i = 0; i < m; i++) {
			int num = moves[i]-1;
			Stack<Integer> stack = board.get(num);
			if(stack.empty()) continue;
			int popNum = stack.pop();
			if(!basket.isEmpty() && basket.peek() == popNum) {
				basket.pop();
				result += 2;
			} else {
				basket.push(popNum);
			}
		}
		System.out.print(result);
		
  }
}

어느 부분에서 틀린지 모르겠습니다. 확인 해주시면 감사하겠습니다.ㅠㅠ