left   = 1
right  = 1000000000
target = (left + right ) / 2
puts "?#{target}"

while right - left >=1
        STDOUT.flush
        respons = gets.to_i
        if respons == 1 then
                left = target
                target = (left + right) / 2
        else
                right = target
                target = (left + right) / 2
        end
        puts "? #{target}"
end

        puts "! #{target}"