/*
    Problem: Guessing the Greatest (easy version)
    Link: https://codeforces.com/contest/1486/problem/C1
*/

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

#define debug(T) cout << ">> " << #T << " = " << (T) << endl;

typedef long long ll;
typedef unsigned long long ull;

// void preprocess() {}

int query(int l, int r) {
    if (l == r) {
        return -1;
    }

    cout << "? " << (l+1) << " " << (r+1) << endl;
    int idx;
    cin >> idx;
    return (idx-1);
}

int search(int l, int r, int smx_idx) { 
    if (l == r) {
        return l;
    }

    int m = (l+r)/2;

    if (smx_idx == -1) {
        smx_idx = query(l, r);
        if (smx_idx == query(l, smx_idx)) {
            return search(l, smx_idx, smx_idx);
        }
        else {
            return search(smx_idx, r, smx_idx);
        }
    }

    if (smx_idx <= m) {
        if (smx_idx == query(smx_idx, m)) {
            return search(l, m, smx_idx);
        }
        else {
            return search(m+1, r, smx_idx);
        }
    }
    else {
        if (smx_idx == query(m+1, smx_idx)) {
            return search(m+1, r, smx_idx);
        }
        else {
            return search(l, m, smx_idx);
        }
    }
}

void solve() {
    int n;
    cin >> n;

    int ans = search(0, n-1, -1);
    cout << "! " << (ans+1) << endl;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int test_case = 1;
    // cin >> test_case;

    // preprocess();
    while (test_case--) {
        solve();
        // cout << endl;
    }

    return 0;
}