program speedrun
  implicit none
  character(100)::S
  logical::CHK=.true.
  integer::i
  read"(A)",S
  do i=1,len_trim(S)
    select case(mod(i,2))
    case(0)
      if(S(i:i)/=" ")CHK=.false.
    case(1)
      if(S(i:i)==" ")CHK=.false.
    end select
  end do
  print"(A)",trim(merge("Yes","No ",CHK))
end program speedrun