local min, max = 1, 100--1000000000
local ret = "1"
while(min ~= max) do
  local mid = math.ceil((min + max) / 2)
  io.write("? " .. mid .. "\n")
  io.flush()
  ret = io.read()
  if(ret == "1") then
    min = mid
  else
    max = mid - 1
  end
end
io.write("! " .. min .. "\n")
io.flush()