using System;
/** SlidePuzzle implements a slide-puzzle game.
  * assumed input: a series of integers between 1 and 15, which indicate the
  *   pieces to move in the slide puzzle
  * guaranteed output: the slide puzzle, as it appears after each move */
public class SlidePuzzle
{ public static void Main()
  {
    int PUZZLE_SIZE = 4;  // how large we make the puzzle

    // the puzzle, where 0 marks the empty space:
    int[,] puzzle = { {15, 14, 13, 12},    // use braces to
                       {11, 10,  9,  8},   // initialize an array
	               { 7,  6,  5,  4},
		       { 3,  2,  1,  0} };

    // Or, build the puzzle like this:
    // int[,] puzzle = new int[PUZZLE_SIZE,PUZZLE_SIZE];

    int empty_x = 3;
    int empty_y = 3;  // the x,y-coordinates of the empty space

    while (true) {

       // use nested for-loops to print the puzzle:	
        for ( int i = 0;  i != PUZZLE_SIZE;  i = i + 1 )
	    { for ( int j = 0;  j != PUZZLE_SIZE; j = j + 1 )
	          { int number = puzzle[i,j];
                    if (number < 10)
                        { Console.Write(" "); }
                    Console.Write( puzzle[i,j]);
                    Console.Write(" "); 
                  }
              Console.WriteLine();
            }

       // ask for the next move:
       Console.Write("Type number of piece to move : ");
       int num = Int32.Parse(Console.ReadLine());

       // search the puzzle for the piece numbered  num:
       int found_x = -1;
       int found_y = -1;
       for ( int i = 0;  i != PUZZLE_SIZE;  i = i + 1 )
           { for ( int j = 0;  j != PUZZLE_SIZE; j = j + 1 )
		 { if ( num == puzzle[i,j] )
		      { found_x = i;
		        found_y = j;
                      }
		 }
           }

       // The previous loops are finished; did we find the piece ?
       if ( found_x == -1 )
          { Console.WriteLine("illegal move --- try again"); }
       else // We did find it, so let's try to move it:
          { // First, check if the piece is adjacent to the empty space
	    if (  ((empty_x == found_x-1) && (empty_y == found_y))
	       || ((empty_x == found_x+1) && (empty_y == found_y))
	       || ((empty_x == found_x) && (empty_y == found_y-1))
	       || ((empty_x == found_x) && (empty_y == found_y+1)) )
               // If true, it's ok to move  num  into the empty space:
	       { puzzle[empty_x,empty_y] = num;
	         puzzle[found_x,found_y] = 0;
		 empty_x = found_x; 
		 empty_y = found_y;
               }
            else { Console.WriteLine("illegal move --- try again"); }
	  }
    }  // end while-loop
  }
}