namespace std {
namespace chrono {
template <class Rep, class Period = ratio<1> > class duration;
template <class Clock, class Duration = typename Clock::duration> class time_point;
}
template <class Rep1, class Period1, class Rep2, class Period2>
struct common_type<chrono::duration<Rep1, Period1>, chrono::duration<Rep2, Period2>>;
template <class Clock, class Duration1, class Duration2>
struct common_type<chrono::time_point<Clock, Duration1>, chrono::time_point<Clock, Duration2>>;
namespace chrono {
template <class Rep> struct treat_as_floating_point;
template <class Rep> struct duration_values;
template <class Rep1, class Period1, class Rep2, class Period2>
typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
constexpr operator+(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period1, class Rep2, class Period2>
typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
constexpr operator-(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period, class Rep2>
duration<typename common_type<Rep1, Rep2>::type, Period>
constexpr operator*(const duration<Rep1, Period>& d, const Rep2& s);
template <class Rep1, class Rep2, class Period>
duration<typename common_type<Rep1, Rep2>::type, Period>
constexpr operator*(const Rep1& s, const duration<Rep2, Period>& d);
template <class Rep1, class Period, class Rep2>
duration<typename common_type<Rep1, Rep2>::type, Period>
constexpr operator/(const duration<Rep1, Period>& d, const Rep2& s);
template <class Rep1, class Period1, class Rep2, class Period2>
typename common_type<Rep1, Rep2>::type
constexpr operator/(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period, class Rep2>
duration<typename common_type<Rep1, Rep2>::type, Period>
constexpr operator%(const duration<Rep1, Period>& d, const Rep2& s);
template <class Rep1, class Period1, class Rep2, class Period2>
typename common_type<duration<Rep1, Period1>, duration<Rep2, Period2>>::type
constexpr operator%(const duration<Rep1, Period1>& lhs, const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period1, class Rep2, class Period2>
constexpr bool operator==(const duration<Rep1, Period1>& lhs,
const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period1, class Rep2, class Period2>
constexpr bool operator!=(const duration<Rep1, Period1>& lhs,
const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period1, class Rep2, class Period2>
constexpr bool operator< (const duration<Rep1, Period1>& lhs,
const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period1, class Rep2, class Period2>
constexpr bool operator<=(const duration<Rep1, Period1>& lhs,
const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period1, class Rep2, class Period2>
constexpr bool operator> (const duration<Rep1, Period1>& lhs,
const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period1, class Rep2, class Period2>
constexpr bool operator>=(const duration<Rep1, Period1>& lhs,
const duration<Rep2, Period2>& rhs);
template <class ToDuration, class Rep, class Period>
constexpr ToDuration duration_cast(const duration<Rep, Period>& d);
typedef duration<signed integer type of at least 64 bits, nano> nanoseconds;
typedef duration<signed integer type of at least 55 bits, micro> microseconds;
typedef duration<signed integer type of at least 45 bits, milli> milliseconds;
typedef duration<signed integer type of at least 35 bits > seconds;
typedef duration<signed integer type of at least 29 bits, ratio< 60>> minutes;
typedef duration<signed integer type of at least 23 bits, ratio<3600>> hours;
template <class Clock, class Duration1, class Rep2, class Period2>
time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
operator+(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
template <class Rep1, class Period1, class Clock, class Duration2>
time_point<Clock, typename common_type<duration<Rep1, Period1>, Duration2>::type>
operator+(const duration<Rep1, Period1>& lhs, const time_point<Clock, Duration2>& rhs);
template <class Clock, class Duration1, class Rep2, class Period2>
time_point<Clock, typename common_type<Duration1, duration<Rep2, Period2>>::type>
operator-(const time_point<Clock, Duration1>& lhs, const duration<Rep2, Period2>& rhs);
template <class Clock, class Duration1, class Duration2>
typename common_type<Duration1, Duration2>::type
operator-(const time_point<Clock, Duration1>& lhs, const time_point<Clock, Duration2>& rhs);
template <class Clock, class Duration1, class Duration2>
bool operator==(const time_point<Clock, Duration1>& lhs,
const time_point<Clock, Duration2>& rhs);
template <class Clock, class Duration1, class Duration2>
bool operator!=(const time_point<Clock, Duration1>& lhs,
const time_point<Clock, Duration2>& rhs);
template <class Clock, class Duration1, class Duration2>
bool operator< (const time_point<Clock, Duration1>& lhs,
const time_point<Clock, Duration2>& rhs);
template <class Clock, class Duration1, class Duration2>
bool operator<=(const time_point<Clock, Duration1>& lhs,
const time_point<Clock, Duration2>& rhs);
template <class Clock, class Duration1, class Duration2>
bool operator> (const time_point<Clock, Duration1>& lhs,
const time_point<Clock, Duration2>& rhs);
template <class Clock, class Duration1, class Duration2>
bool operator>=(const time_point<Clock, Duration1>& lhs,
const time_point<Clock, Duration2>& rhs);
template <class ToDuration, class Clock, class Duration>
time_point<Clock, ToDuration> time_point_cast(const time_point<Clock, Duration>& t);
class system_clock;
class steady_clock;
class high_resolution_clock;
} }