using System;
public class Test
{
public static void Main()
{
string example = "aaaaaaaaXbbbbXaaaaaa";
int firstXposition = example.IndexOf("X");
int LastXposition = example.LastIndexOf("X");
Console.WriteLine(example.Substring(firstXposition + 1, LastXposition - firstXposition -1));
}
}
dXNpbmcgU3lzdGVtOwoKcHVibGljIGNsYXNzIFRlc3QKewoJcHVibGljIHN0YXRpYyB2b2lkIE1haW4oKQoJewoJCXN0cmluZyBleGFtcGxlID0gImFhYWFhYWFhWGJiYmJYYWFhYWFhIjsKICAgICAgICAgICAgICAgIGludCBmaXJzdFhwb3NpdGlvbiA9IGV4YW1wbGUuSW5kZXhPZigiWCIpOwogICAgICAgICAgICAgICAgaW50IExhc3RYcG9zaXRpb24gPSBleGFtcGxlLkxhc3RJbmRleE9mKCJYIik7CiAgICAgICAgICAgICAgICBDb25zb2xlLldyaXRlTGluZShleGFtcGxlLlN1YnN0cmluZyhmaXJzdFhwb3NpdGlvbiArIDEsIExhc3RYcG9zaXRpb24gLSBmaXJzdFhwb3NpdGlvbiAtMSkpOwoKCgl9Cn0=