The classic game of Concentration

Run this program by typing at a command prompt

tc concen.tc

You will be asked to enter a random number.

You will see a 4x4 array of x's. You will type two pairs of numbers
representing the row and column locations of your guess. You are shown
the two letters which lie under your choices. You might see for example
the letters b and h. If they match, your score goes up by 1. Whether
they match or not, it is now the next player's turn. The game ends when
the total of the two players' scores is 8.

On each turn the top of the board is displayed. Any "cards" that have
been matched appear as spaces, all others as x's.

The winner is declared at the end of the game, or a tie is announced.

Here's the beginning of a sample run.

tc concen.tc

player 1 : 0    player 2 : 0

xxxx
xxxx
xxxx
xxxx

player 1, your turn

row 1 (1..4) ? 3
col 1 (1..4) ? 1
row 2 (1..4) ? 1
col 2 (1..4) ? 3

  b

c


player 1 : 0    player 2 : 0

xxxx
xxxx
xxxx
xxxx

player 2, your turn

row 1 (1..4) ? 1
col 1 (1..4) ? 1
row 2 (1..4) ? 1
col 2 (1..4) ? 2

ch




player 1 : 0    player 2 : 0

xxxx
xxxx
xxxx
xxxx

player 1, your turn

row 1 (1..4) ? 1
col 1 (1..4) ? 1
row 2 (1..4) ? 3
col 2 (1..4) ? 1

c

c


player 1 : 1    player 2 : 0

 xxx
xxxx
 xxx
xxxx

player 2, your turn

row 1 (1..4) ?