local function query(num)
  io.write("? " .. num .. "\n")
  io.flush()
  local ret = io.read("*l")
  ret = tonumber(ret)
  local a_minus_b = ret - (num - ret)
  return a_minus_b
end
local function ans(l, r)
  io.write("! " .. l .. " " .. r .. "\n")
  io.flush()
  os.exit()
end

local n = io.read("*n", "*l")
local left, right = 1, n - 1
local lv = query(left)
local rv = query(right)
if lv == rv then
  ans(left, right)
end
local hn = math.floor(n / 2)
for i = 1, 18 do
  local mid = math.floor((left + right) / 2)
  local mv = query(mid)
  if mv == 0 then
    if hn <= mid then
      ans(1, mid)
    else
      ans(mid, n)
    end
  else
    if mv * lv < 0 then
      right = mid
    else
      left = mid
    end
  end
end