import java.util.Scanner;

/** 
Class to verify solutions to Sudoku puzzles. Correct solutions have the 
numbers 1..9 in each row, column, and 9 squares of 3x3.

A putative solution is read in from stdin, and yay or nay is printed out.
Used as an example to illustrate 2D arrays and scanners for cs136.

@author Stacia K. Wyman 2006
*/

public class SudokuVerifier{
    /** constant grid size: 9x9 */
    public final static int SIZE = 9;
    /** board is a 9x9 2D array to hold the solution */
    protected int board[][];

    /** constructor simply allocates the array */
    public SudokuVerifier(){
	board = new int[SIZE][SIZE];
    }

    /** Check row verifies each row one by one
	@pre    board contains a solution
	@post   testing post tag
	@return true if rows check out, false o/w */
    protected boolean checkRows(){
	for (int row = 0; row < SIZE; row++){
	    for (int i = 0; i < SIZE; i++){
		int count = 0;
		for (int col = 0; col < SIZE; col++){
		    if (board[row][col] == i){
			count++;
		    }
		}
		if (count != 1){
		    return false;
		}
	    }   
        }
	return true;
    }

    /** Check columns verifies that each column contains 1-9 uniquely
	@pre rows checked out
	@post now rows and cols check out, just subsquares left to check
	@return true if all columns contain 1-9 uniquely
    */
    protected boolean checkCols(){
        for (int col = 0; col < SIZE; col++){
            for (int i = 0; i < SIZE; i++){
                int count = 0;
                for (int row = 0; row < SIZE; row++){
                    if (board[row][col] == i){
                        count++;
                    }
                }
                if (count != 1){
                    return false;
                }
            }
        }
        return true;
    }



    protected boolean checkBlocks(){
	
	// an exercise left for the reader
	// What's a good way to verify the blocks?















	return true;
    }


    public static void main(String[] args){
	Scanner s = new Scanner(System.in);
	SudokuVerifier game = new SudokuVerifier();
	int row = 0;
	int col = 0;

	// read in the board from a file 
	while (s.hasNextLine()){
	    String line = s.nextLine();
	    Scanner t = new Scanner(line);
	    while (t.hasNextInt()){
		int num = t.nextInt();
		game.board[row][col] = num - 1;
		col++;
	    }
	    col = 0;
	    row++;
       }

	if (game.checkRows() && game.checkCols() && game.checkBlocks()){
	    System.out.println("It's a solution!");
	}else{
	    System.out.println("Not a solution. Sorry.");
	}

    }
}