program DateToUnixTimestamp
        implicit none
        integer :: year, month, day, hour, minute, second
        integer(8) :: unix_timestamp
        integer(8) :: days_since_epoch, seconds_since_midnight
        integer, parameter :: epoch_start = 719163  ! Julian day number for 1970-01-01

        ! Example date and time
        year = 2024
        month = 8
        day = 28
        hour = 12
        minute = 34
        second = 56

        ! Calculate the number of days since the Unix epoch
        days_since_epoch = julday(year, month, day) - epoch_start

        ! Calculate the number of seconds since midnight
        seconds_since_midnight = hour * 3600 + minute * 60 + second

        ! Calculate the Unix timestamp
        unix_timestamp = days_since_epoch * 86400 + seconds_since_midnight

        print *, "Unix Timestamp: ", unix_timestamp
    end program DateToUnixTimestamp

    ! Function to calculate Julian day number for a given Gregorian date
    integer function julday(year, month, day)
        implicit none
        integer, intent(in) :: year, month, day
        integer :: a, y, m

        a = (14 - month) / 12
        y = year + 4800 - a
        m = month + 12 * a - 3  

        julday = day + ((153 * m + 2) / 5) + 365 * y + (y / 4) - (y / 100) + (y / 400) - 32045
    end function julday