program main
  implicit none
  integer i, N, X, T
  read(*, *)N, X, T
  !read(*, *) (L(i), i = 1,N)
  if (mod(N,X) == 0) then
  	write(*, *)(N/X)*T
    else
    write(*, *)(N/X+1)*T
    endif
end program main
