#include<iostream>
#include<cstdio>
#include<vector>
#include<queue>
#include<map>
#include<string>
#include<algorithm>
#include<functional>
using namespace std;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define INF 1<<30
#define MP make_pair
#define mp make_pair
#define pb push_back
#define PB push_back
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define ll long long
#define ull unsigned long long

int main(){
	int r,l,mid;
	r=1000000000,l=0;
	while(r!=l){
		mid=(r+l)/2;
		printf("? %d", mid);
		cout<<flush;
		int f;
		scanf("%d",&f);
//  		int f=0;
//  		if(x>=mid) f=1;
		if(f) l=mid+1;
		if(!f) r=mid;
	}
	cout<<"! " << mid<<endl;
	return 0;
}