program main
 implicit none
 integer(8) H,W
 integer(8) A
 integer(8) kari1,kari2,kari3

 read *,H,W

!if (H==1 .or. W==1) then
! print '(i0)',1
! stop
!end if

  kari1=floor(0.5*H)
  kari2=ceiling(0.5*W)
  kari3=floor(0.5*W)
 if ( mod(H,2) == 0 ) then
  A=kari1*kari2 + kari1*kari3
 else
  A=kari1*kari2 + kari1*kari3 + kari2
 end if

 print '(i0)', A

endprogram main
