program sumo
 implicit none
 character(15) :: s
 integer n, m, i, k, win
 m=0
 read*, s
 k=len_trim(s)
 do i=1,k
  n=index(s(i:i),"o")
   if(n.ne.0) m=m+1
 end do
 win=m+(15-k)
 if(win.ge.8) then
  write(*,*) "YES"
 else if (win.lt.8) then
  write(*,*) "NO"
 end if
end program