import java.io.*;
import java.util.*;
class Solution {
public int solution(int[][] board, int[] moves) {
Stack<Integer> stack = new Stack<>();
int size = board.length;
int answer = 0;
//moves
for( int k = 0 ; k < moves.length ; k++){
int temp = moves[k];
for(int i = 0 ; i < size ; i ++){
if(board[i][temp-1] != 0){
if(!stack.isEmpty() && stack.peek() == board[i][temp-1]){
answer+= 2;
stack.pop();
}else{
stack.push(board[i][temp-1]);
}
board[i][temp-1] = 0;
break;
}
}
}
return answer;
}
}