public static String ToBase36(UInt64 input)
{
const String CharList = "0123456789abcdefghijklmnopqrstuvwxyz";
char[] clistarr = CharList.ToCharArray();
var result = new Stack <char>();
while (input != 0)
{
result.Push(clistarr[input % 36]);
input /= 36;
}
return(new String(result.ToArray()));
}