program main
  implicit none
  integer*8::N,i
  integer*8::lower=1,mid,upper=10**9
  do i=1,101
     mid = (lower+upper)/2_8

     print '("? ",i0)',mid
     read *,N
     if(N.eq.1) then
        lower=mid
     else
        upper=mid
     end if
     if(upper.le.lower+1) exit
  end do
  print '("! ",i0)',lower
end program main