#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;

int main() {
	/*freopen("in.txt", "r", stdin);
	freopen("out.txt", "w", stdout);*/
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n;
	cin >> n;
	int l = 1, r = n;
	auto ask = [&](int i, int j) {
		cout << "? " << i << ' ' << j << endl;
		int val;
		cin >> val;
		return val;
	};
	int smax = ask(l, r), mid = -1;
	if (l != smax && ask(l, smax) == smax) {
		r = smax;
		while (l + 1 < r) {
			mid = (l + r) / 2;
			if (ask(mid, smax) == smax)
				l = mid;
			else
				r = mid;
		}
		cout << "! " << l << endl;
	}
	else {
		l = smax;
		while (l + 1 < r) {
			mid = (l + r) / 2;
			if (ask(smax, mid) == smax)
				r = mid;
			else
				l = mid;
		}
		cout << "! " << r << endl;
	}
}