package main

import (
	"fmt"
)


func main() {
	solve()
}

func ask(x int)int{
	fmt.Println("?",x)
	var y int
	fmt.Scan(&y)
	return y
}

func solve(){
	lb := -1
	ub := 1000000000
	for i:=0; i<100; i++{
		mid := (lb+ub)/2
		ans := ask(mid)
		if ans==-1{
			ub = mid-1
		}
		if ans==1{
			lb = mid-1
		}
		if ans == 0{
			fmt.Println("!", ans+i)
			break
		}
	}
}