using System;
public class Program
{
public static void Main()
for(ulong i = 0; i <= 63; i++) {
ulong size = Convert.ToUInt64(Math.Pow(2, i));
ulong area = size*size;
if((area-1)/3 == Convert.ToUInt64((area-1)/3))
Console.WriteLine("{0}) {1}x{1} is valid", i+1, size);
} //End loop
} //End Main()
} //End program