#include <bits/stdc++.h>

using namespace std;

using pii = pair<int, int>;
using ll = long long;
const int N = 2000010, MOD = 998244353, INF = 0x3f3f3f3f;
int n, m, w[N];

int ask(int x) {
    printf("? %d\n", x);
    fflush(stdout);
    scanf("%d", &x);
    return x;
}

void solve() {
    int l = ask(0), r = ask(1);
    if (l < r) printf("! %d\n", -l);
    else printf("! %d\n", l);
    fflush(stdout);
}

int main() {
    int T;
    // scanf("%d", &T);
    while (T--) solve();
    return 0;
}