local function query(str)
  io.write(str .. "\n")
  io.flush()
  local ret = io.read("*l")
  return ret
end

local min, max = 1, 1000000001
while 1 < max - min do
  local mid = math.floor((min + max) / 2)
  local qstr = "? " .. mid
  local ans = query(qstr)
  if ans == "1" then
    min = mid
  else
    max = mid
  end
end
print("! " .. min)