#include <iostream>
#include <algorithm>
#include <cstring>
#include <sstream>
#include <map>
#include <queue>
#include <set>
#include <vector>
#include <stack>
#include <cstdio>
#include <cmath>
#include <bitset>
#define mk make_pair
#define pb push_back
using namespace std;
typedef long long int ll;
typedef pair<ll, ll> pos;

const ll MOD = 1234567, N = 100010, dx[4] = { -1,1,0,0 }, dy[4] = { 0,0,-1,1 }, MIN = -72340172838, MAX = 72340172838;

ll mn(ll a, ll b) {
	if (a == -1)return b;
	if (b == -1)return a;
	return min(a, b);
}
ll gcd(ll v1, ll v2) {
	if (v1 == 0)return v2; if (v2 == 0)return v1; if (v2 > v1)return gcd(v2%v1, v1); return gcd(v1%v2, v2);
}

ll pw(ll v1, ll v2) {
	ll v3 = 1;
	while (v2 > 0) {
		if (v2 % 2)v3 = (v3*v1) % MOD;
		v1 = (v1*v1) % MOD;
		v2 /= 2;
	}
	return v3;
}

struct ab {
	ll a, b;
	bool operator<(const ab& right) const {
		return right.b*a - right.a*b < 0;
	}
};

ll mnv = 0, mxv = 1000000001;

bool ok(ll md) {
	cout << "? " << md << endl;
	ll v1; cin >> v1;
	cout.flush();
	return (v1==1);
}

int main() {
	while (mxv - mnv > 1) {
		ll md = (mxv + mnv) / 2;
		if (ok(md))mnv = md;
		else mxv = md;
	}
	cout <<"! "<< mnv << endl;
	return 0;
}