#include <iostream>
#include <regex>
#include <string>
int main()
{
std::basic_string<char> reg = "^\\w";
std::basic_regex<char> tagRegex(reg);
return 0;
}
ICAgICNpbmNsdWRlIDxpb3N0cmVhbT4KICAgICNpbmNsdWRlIDxyZWdleD4KICAgICNpbmNsdWRlIDxzdHJpbmc+CgogICAgaW50IG1haW4oKQogICAgewogICAgICAgIHN0ZDo6YmFzaWNfc3RyaW5nPGNoYXI+IHJlZyA9ICJeXFx3IjsKCiAgICAgICAgICAgIHN0ZDo6YmFzaWNfcmVnZXg8Y2hhcj4gdGFnUmVnZXgocmVnKTsKCiAgICAgICAgcmV0dXJuIDA7CiAgICB9