#include <bits/stdc++.h>
#include <chrono>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
template <typename T >
using oset = tree < T, null_type, less < T > , rb_tree_tag, tree_order_statistics_node_update > ;
#define int long long
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
//#define endl '\n'
using ll = long long;
using ld = long double;
#define send ios::sync_with_stdio(false);
#define help cin.tie(0);
void solve(int T);
const int N = 1e5 + 10;
const int M = 405;
const int SQRT = sqrt(N);
const int LOG = 20;
const int INF = 1e18;
const int MOD = 45678;
const ld EPS = 1e-9;
int ans;
int n, m, q, l, r, x, y, mx, mn;
int32_t main(){
send help;
solve(1);
}
bool ask(int l,int r){
if(l < 0 || r >= n)return 0;
cout<<"? "<<l+1<<" "<<r+1<<endl;
bool a;
cin>>a;
return a;
}
void answer(int x){
cout<<"! "<<x<<endl;
exit(0);
}
void solve(int T){
cin>>n;
int o = 0;
int e = 0;
for(int i = 0;i<n;i++){
while(ask(i - o - 1, i + o + 1))o++;
while(ask(i - e, i + e + 1))e++;
}
answer(max(o * 2 + 1, 2 * e));
}
//Te molam da raboti !!
