using System;
using System.Text.RegularExpressions;
public class Test
{
public static void Main()
{
Console.WriteLine(Regex.Matches("hello a5 world", "\\ba5\\b").Count > 0);
Console.WriteLine(Regex.Matches("hello a55 world", "\\ba5\\b").Count > 0);
Console.WriteLine(Regex.Matches("hello xa5 world", "\\ba5\\b").Count > 0);
}
}
dXNpbmcgU3lzdGVtOwp1c2luZyBTeXN0ZW0uVGV4dC5SZWd1bGFyRXhwcmVzc2lvbnM7CgpwdWJsaWMgY2xhc3MgVGVzdAp7CglwdWJsaWMgc3RhdGljIHZvaWQgTWFpbigpCgl7CgkJQ29uc29sZS5Xcml0ZUxpbmUoUmVnZXguTWF0Y2hlcygiaGVsbG8gYTUgd29ybGQiLCAiXFxiYTVcXGIiKS5Db3VudCA+IDApOwogICAgCUNvbnNvbGUuV3JpdGVMaW5lKFJlZ2V4Lk1hdGNoZXMoImhlbGxvIGE1NSB3b3JsZCIsICJcXGJhNVxcYiIpLkNvdW50ID4gMCk7CiAgICAJQ29uc29sZS5Xcml0ZUxpbmUoUmVnZXguTWF0Y2hlcygiaGVsbG8geGE1IHdvcmxkIiwgIlxcYmE1XFxiIikuQ291bnQgPiAwKTsKCX0KfQ==