public static String gridChallenge(List<String> grid) {
// Write your code here
    List<String> squareMatrixList = new ArrayList<>();
    //row sorting
    for(int i =0; i < grid.size(); i ++){
       char[] rowsorted = grid.get(i).toCharArray();
       Arrays.sort(rowsorted);
       squareMatrixList.add(String.valueOf(rowsorted));
    }
    System.out.println(squareMatrixList.toString());
    int size = squareMatrixList.size();
    int strLength = squareMatrixList.get(0).length();
    for(int col =0; col < strLength; col++){
        for(int row = 0; row < size -1; row++){
            String str1 = squareMatrixList.get(row);
            String str2 = squareMatrixList.get(row +1);
            if(str1.charAt(col) > str2.charAt(col)){
                return "NO";
            }
        }
    }
    return "YES";
}