#include <chrono>
#include <iostream>
#include <string>
#include <string_view>

class TimerGuard {
private:
    std::string message_;
    std::ostream &out_;
    using Clock = std::chrono::high_resolution_clock;
    std::chrono::time_point<Clock> start_;
public:
    TimerGuard(std::string_view message = "",
               std::ostream &out = std::cout) : message_(message),
                                                out_(out),
                                                start_(Clock::now()) {
        out_ << "{" << message_ << "}" << " ";
    }

    ~TimerGuard() {
        std::chrono::duration<double> diff = std::chrono::high_resolution_clock::now() - start_;
        out_ << "{" <<
             diff.count() <<
             "}";
    }
};