program main
  implicit none
  integer::n(1:4),m(1:4)
  integer::hit,blow,phit,pblow,i,j
  data n/0,1,2,3/

  call get(n,hit,blow)
  if(hit.eq.4) return

! selection
  if(hit+blow.ne.4) then
     do i=1,4
        phit = hit
        pblow = blow
        m = n
        do j=0,9
           if(ANY(n.eq.j)) cycle
           m(i) = j
           call get(m,hit,blow)
           if(hit+blow.eq.4) then
              n = m
              goto 10
           else if(hit+blow.gt.phit+pblow) then
              n = m
              exit
           end if
        end do
     end do
  end if
10 continue
  ! shuffle
  m = n
  n = qsort(m)
  do
     call get(n,hit,blow)
     if(hit.eq.4) then
        return
     end if
     call next_permutation(n)
  end do
contains
  subroutine get(n,hit,blow)
    integer::n(1:4)
    integer::hit,blow
    print '(i0," ",i0," ",i0," ",i0)',n
    read *,hit,blow
  end subroutine get
  subroutine next_permutation(array)
    implicit none
    integer::array(:),d,i,j,k,swap
    d = 4

    do i=d,2,-1
       if(array(i-1).lt.array(i)) exit
    end do
    do j=d,i+1,-1
       if(array(i-1).lt.array(j)) exit
    end do

    swap       = array(i-1)
    array(i-1) = array(j)
    array(j)   = swap
    do k=0, (d-1-i)/2
       swap       = array(i+k)
       array(i+k) = array(d-k)
       array(d-k) = swap
    end do
  end subroutine next_permutation
  recursive function qsort(x) result(y)
    integer,intent(in) ::x(:)
    integer,allocatable::y(:)
    integer::pivot,total
    total = size(x)
    if (total <=1) then
       y = x
    else
       pivot = x(total/2)
       y = [qsort(pack(x, x .lt. pivot)), &
            pack(x, x .eq. pivot),        &
            qsort(pack(x, x .gt. pivot))]
    endif
  end function qsort
end program main