Write a program that will allow two users to play tic-tac-toe. The program should ask for moves alternately from player X and player O. The program displays the game position as follows:
1 2 3
4 5 6
7 8 9
The players enter their moves by entering the position number they wish to mark. After each move, the program displays the changed board. A sample board configuration is as follows:
X X 0
4 5 6
0 9 9