text: //play_2D.cpp
  #include <string>
  #include <iostream>
  #include "ttt2D.h"
  
  using namespace std;
  
  int main(int argc, char *argv[]) {
      if (argc != 2) {
          cerr << "  Usage: " << argv[0] << " [size]\n";
          exit(1);
      }
      int size = stoi(argv[1]);
      // begins the game of tic tac toe
      string player1 = namePlayer_2D(1);
      string player2 = namePlayer_2D(2);
      ttt2D(player1, player2, size);
      return 0;
  }