program panasonic2020b
    use,intrinsic :: iso_fortran_env
    implicit none
    integer(int64):: h,w
    
    read*, h,w
    if (h==1 .or. w==1) then
        print'(i0)', 1
    else
        print'(i0)', h*w - (h*w)/2
    end if
end program panasonic2020b