#include <iostream>
#include <tuple>
#include <random>
#include <cmath>
#include <numeric>
#include <cassert>
#include <iomanip>
#include <algorithm>
#include <set>

#define sz(a) (int)(a).size()
#define all(a) begin(a), end(a)

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;

ll dist(int x1, int y1, int x2, int y2) {
    return abs(x1 - x2) + abs(y1 - y2);
}

int main() {
#ifdef LOCAL
//    freopen("input.txt", "r", stdin);
#endif

    int n;
    cin >> n;

    cout << "? " << 1 << " " << n << endl;
    int m;
    cin >> m;

    bool is_lefter = false;

    if (m > 1) {
        cout << "? " << 1 << " " << m << endl;
        int ans;
        cin >> ans;
        if (ans == m) {
            is_lefter = true;
        }
    }

    if (is_lefter) {
        int l = 1;
        int r = m;
        while (r - l > 1) {
            int q = (l + r) / 2;
            cout << "? " << q << " " << m << endl;
            int ans;
            cin >> ans;
            if (ans == m) {
                l = q;
            } else {
                r = q;
            }
        }
        cout << "! " << l << endl;
    } else {
        int l = m;
        int r = n;
        while (r - l > 1) {
            int q = (l + r) / 2;
            cout << "? " << m << " " << q << endl;
            int ans;
            cin >> ans;
            if (ans == m) {
                r = q;
            } else {
                l = q;
            }
        }
        cout << "! " << r << endl;
    }

    return 0;
}