#include <iostream>
#include <regex>
using namespace std;
 
int main() {
	const std::regex pattern("[^a-zA-Z0-9.-_]");
	std::string String = "!#!e-ma.il@boomer.com";
	// std::regex_constants::icase
	// std::string newtext = std::regex_replace( String, pattern, "X", std::regex_constants::format_first_only );
	std::string newtext = std::regex_replace( String, pattern, "", std::regex_constants::icase);
	std::cout << newtext << std::endl;
	return 0;
}