using System;
using System.Text.RegularExpressions;
public class Test
{
public static void Main()
{
string str = "11111111111111";
string result = Regex.Replace(str, @"(?:^(.{6})|\G).(?=.{4})", "$1*");
Console.WriteLine(result);
Console.ReadLine();
}
}
dXNpbmcgU3lzdGVtOwp1c2luZyBTeXN0ZW0uVGV4dC5SZWd1bGFyRXhwcmVzc2lvbnM7CiAKcHVibGljIGNsYXNzIFRlc3QKewpwdWJsaWMgc3RhdGljIHZvaWQgTWFpbigpCnsKc3RyaW5nIHN0ciA9ICIxMTExMTExMTExMTExMSI7CnN0cmluZyByZXN1bHQgPSBSZWdleC5SZXBsYWNlKHN0ciwgQCIoPzpeKC57Nn0pfFxHKS4oPz0uezR9KSIsICIkMSoiKTsKQ29uc29sZS5Xcml0ZUxpbmUocmVzdWx0KTsKQ29uc29sZS5SZWFkTGluZSgpOwp9Cn0=