using System;

public class Program

{

    public static void Main()

    {

        string frstStr = "X";

        string secStr = "O";

        string tempStr = "X";

​

for(int i= 1; i < 9; i++)

{

for(int j= 1; j < 9; j++)

{

if(j % 2 == 0)

Console.Write(secStr);

else 

Console.Write(frstStr);

}

frstStr = secStr;

secStr = tempStr;

tempStr = frstStr;

Console.WriteLine();

}

    }

}