using System;
using System.Text.RegularExpressions;
public class Test
{
public static void Main()
{
var str = "United a States of America if";
var pieces = Regex.Split(str, " (?!of|a|if)");
foreach (var piece in pieces) {
Console.WriteLine(piece);
}
}
}
dXNpbmcgU3lzdGVtOwp1c2luZyBTeXN0ZW0uVGV4dC5SZWd1bGFyRXhwcmVzc2lvbnM7CgpwdWJsaWMgY2xhc3MgVGVzdAp7CglwdWJsaWMgc3RhdGljIHZvaWQgTWFpbigpCgl7CiAgICAgICAgdmFyIHN0ciA9ICJVbml0ZWQgYSBTdGF0ZXMgb2YgQW1lcmljYSBpZiI7CiAgICAgICAgdmFyIHBpZWNlcyA9IFJlZ2V4LlNwbGl0KHN0ciwgIiAoPyFvZnxhfGlmKSIpOwogICAgICAgIAogICAgICAgIGZvcmVhY2ggKHZhciBwaWVjZSBpbiBwaWVjZXMpIHsKICAgICAgICAgICAgQ29uc29sZS5Xcml0ZUxpbmUocGllY2UpOwogICAgICAgIH0KCX0KfQ==