program day
    implicit none
    integer, parameter :: max_chars = 300
    character(200) :: fname
    character(max_chars) :: fline
    integer :: n_arguments
    integer :: istat

    n_arguments = command_argument_count()
    if (n_arguments .eq. 1) then
        call get_command_argument(1, fname)
        print *, "File: ", trim(fname)
        print *
    else
        print *, "Wrong number of arguments: ", n_arguments
        stop
    end if
end program day