#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
const int mod = 1e9 + 7;
const int inf = 0x7fffffff;

// Never give up, keep going.

int query(int l, int r) {
  cout << "? " << l << " " << r << endl;
  int ans;
  cin >> ans;
  return ans;
}

void solve() {
  int n, p;
  cin >> n;
  cout << "? " << 1 << " " << n << endl;
  cin >> p;
  int l = 1, r = n;
  p = query(l, r);
  if (p != 1 && p == query(1, p)) {
    l = 1, r = p;
    while (l + 1 < r) {
      int m = l + r >> 1;
      if (p == query(m, p))
        l = m;
      else
        r = m;
    }
    cout << "! " << l << endl;
  } else {
    l = p, r = n;
    while (l + 1 < r) {
      int m = l + r >> 1;
      if (p == query(p, m))
        r = m;
      else
        l = m;
    }
    cout << "! " << r << endl;
  }
}

int main() {
  ios::sync_with_stdio(false);
  solve();
  return 0;
}