chiffre manquant dans chaque colonne matrice

import java.util.*;
import java.io.*;
import java.math.*;

class Solution
{

    public static void main(String args[])
    {
        Scanner in = new Scanner(System.in);
        char[][] matrix = new char[9][9];
        Map<Integer, Boolean> map = new HashMap<>();

        for (int i = 0; i < 9; i++)
        {
            String w = in.nextLine();
            for(int j = 0; j < 9; j++)
                matrix[i][j] = w.charAt(j);
        }
        for(int i = 0; i < 9; i++)
        {
            for(int k = 1; k <= 9; k++)
                map.put(k,false);
            for(int j = 0; j < 9; j++)
                if(Character.isDigit(matrix[j][i]))
                    map.put(matrix[j][i]-'0',true);
            for(int x : map.keySet())
                if(map.get(x) == false)
                    System.out.print(x);
        }

    }
}