#include <bits/stdc++.h>
#define ll long long
using namespace std;

int ask(int l, int r) {
    int pos;
    cout << "? " << l << ' ' << r << endl;
    cin >> pos;
    return pos;
}

int main() {
    int n;

    cin >> n;
    int secondMax = ask(1, n), left, right;
    if (secondMax == 1 || ask(1, secondMax) != secondMax) {
        left = secondMax, right = n;
        while (left + 1 < right) {
            int mid = (left + right) / 2;

            if (ask(secondMax, mid) == secondMax)
                right = mid;
            else
                left = mid;
        }

        cout << "! " << right << endl;
    } else {
        left = 1, right = secondMax;
        while (left + 1 < right) {
            int mid = (left + right) / 2;

            if (ask(mid, secondMax) == secondMax)
                left = mid;
            else
                right = mid;
        }

        cout << "! " << left << endl;
    }

    return 0;
}
