#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES

#include "bits/stdc++.h"
#define REP(i,a,b) for(int i=a;i<b;++i)
#define rep(i,n) REP(i,0,n)
#define ll long long
#define ull unsigned ll
typedef long double ld;
#define ALL(a) begin(a),end(a)
#define ifnot(a) if(not a)
#define dump(x)  cerr << #x << " = " << (x) << endl
using namespace std;

// #define int ll
#ifdef _MSC_VER
const bool test = true;
#else 
const bool test = false;
#endif

int dx[] = { 0,1,0,-1 };
int dy[] = { 1,0,-1,0 };
#define INF (1 << 28)
ull mod = (int)1e9 + 7;
//.....................
#define MAX (int)1e6 + 5

int length = 5;

void question(int Y) {
	cout << "? " << Y << endl;	
	cerr << "please print ";
	if (length < Y) cerr << -1;
	if (length > Y) cerr << 1;
	if (length == Y) cerr << 0;
	cerr << endl;
	length--;
}

void ans(int Y) {
	cout << "! " << Y << endl;
	exit(0);
}

signed main() {
	int cnt = 0;
	int left = 0, right = INT_MAX;
	rep(i, 30) {
		question(1 << i);
		int res;
		cin >> res;
		if (res == 0) ans((1 << i) + i);
		if (res == -1) {
			right = (1 << i) - 1;
			cnt = i + 1;
			break;
		}
	}
	if (right == INT_MAX) cnt = 6;

	rep(i, 1000) {
		int mid = (left + right) / 2;
		dump(left);
		dump(right);
		dump(mid);
		question(mid);
		int res;
		cin >> res;
		if (res == -1) {
			right = mid;
		}
		if (res == 1) {
			left = mid;
		}
		if (res == 0) {
			ans(mid + i + cnt);
		}
		left--;
		right--;
	}
	return 0;
}