import scala.io.StdIn.readLine
import scala.collection.mutable.PriorityQueue
import scala.annotation.tailrec

// PriorityQueue[Long]()(scala.math.Ordering.Long.reverse)
package net.pushl {
  package number {
    // Prime  (Prime.scala)
    // Number (Number.scala)
  }
  package string {
    // RollingHash (RollingHash.scala)
  }
  object EnRich {
    implicit class AString(val self : String) extends AnyVal {
      def splitToIntArray = self.split(" ").map(_.toInt)
    }
  }
}

object Main {
  def main(args : Array[String]) : Unit = {
    var lower = 0           // lower < x
    // var upper = 100  // x <= upper
    var upper = 1000000010  // x <= upper

    for(i <- 0 to 80){
      val mid = (lower+upper)/2
      println(s"? $mid")
      Console.flush()
      val mid_is_greater_than_or_equal_to_x = readLine() == "1"
      if(mid_is_greater_than_or_equal_to_x){
        lower = mid
      }else{
        upper = mid
      }
    }
    println(s"! $lower")
    Console.flush()
  }
}