TicTacToe but in C#

using System;
class HelloWorld {
  static void Main() {
    string [,] lines = {
        {"1", "2", "3"},
        {"4", "5", "6"},
        {"7", "8", "9"}
    };
    bool won = false, xWinner = false, oWinner = false, turn = false;
    string action;
    do {
        //Prints out the Board
        int f = 0;
        int t = 0;
        Console.Clear();
        foreach (string x in lines) {
            f++;
            if (f == lines.GetLength(1)) {
                t++;
                Console.WriteLine(x);
                if (t != lines.GetLength(0)) {
                    for (int y = 0; y < 3 * lines.GetLength(1); y++) {
                        Console.Write("-");
                    }
                    Console.Write("\n");
                }
                f = 0;
            } else {
                Console.Write(x + " | ");
            }
        };

        //Input
        action = Console.ReadLine();
        if (!(action == "X" || action == "x" || action == "O" || action == "o")) {
            int pop = 0;
            int bop = 0;
            foreach (string xx in lines) {
                pop++;
                if (pop > lines.GetLength(1)) {
                    pop = 0;
                    bop++;
                }
                if (lines[bop, pop] == action) {
                    if (turn) {
                        lines[bop, pop] = "X";
                    } else {
                        lines[bop, pop] = "O";
                    }
                }
            }
        };

        //Checks for win
        for (int xxx = 0; xxx < lines.GetLength(0); xxx++) {
            for (int yyy = 0; yyy < lines.GetLength(1); yyy++) {
                //Checks horizontally
                if (lines.GetLength(1) - yyy < 3) {
                    if ((lines[xxx, yyy] == lines[xxx, yyy + 1] && lines[xxx, yyy + 1] == lines[xxx, yyy + 2]) || (lines[xxx, yyy + 3] == lines[xxx - 1, yyy + 2] && lines[xxx - 1, yyy + 2] == lines[xxx, yyy + 3])) {
                        if (lines[xxx, yyy] == "X") {
                            xWinner = true;
                        } else {
                            oWinner = true;
                        }
                        won = true;
                    }
                }

                //Checks Vertically
                if (lines.GetLength(0) - xxx < 3) {
                    if (lines[xxx, yyy] == lines[xxx + 1, yyy] && lines[xxx + 1, yyy] == lines[xxx + 2, yyy]) {
                        if (lines[xxx, yyy] == "X") {
                            xWinner = true;
                        } else {
                            oWinner = true;
                        }
                        won = true;
                    }
                }
            }
        }
    } while (!won);

    //Checks for no winner / draw / tie
    if (xWinner || oWinner) {
        if (xWinner) {
            Console.Write("X has won!");
        } else {
            Console.Write("O has won!");
        }
    } else {
        Console.Write("Nobody won!");
    }
    Console.ReadLine();
  }
}