def findFavNum(a,b)
    if (a-b).abs <= 1 then
        print("? #{b}")
        if gets.to_i == 1 then
            print("! #{b}")
            return
        else
            print("! #{a}")
            return
        end
    end

    if a<b then
        range_left = a
        range_right = b
    else
        range_left = b
        range_right = a
    end

    
    middle = ((range_left-range_right).abs+1)/2 + range_left
    print("? #{middle}")
    if gets.to_i == 1 then
        findFavNum(middle,range_right)
    else
        findFavNum(range_left,middle-1)
    end
end

findFavNum(1,10)