#include <bits/stdc++.h>
#define pb push_back
#define ll long long
#define vll vector<ll>
#define vbool vector<bool>
#define pairll pair<ll,ll>
#define fi first
#define sc second
#define rever greater<ll>()
using namespace std;
void solve(){
ll n; cin >> n;
vll a(n*2, 1); ll x;
for(ll i = 2; i < n*2;){
if((i+(a[i]/2+1)) > n*2)break;
if(i-(a[i]/2+1) >= 1){
if((i-(a[i]/2+1))%2 == 0){
a[i]+=2; continue;
}
//cout << i << ' ' << a[i] << endl;
cout << "? " << (i-(a[i]/2+1))/2+1 << ' ' << (i+(a[i]/2+1))/2+1 << endl;
fflush(stdout);
cin >> x;
if(x){
a[i]+=2; continue;
}
}
ll k = (a[i]/2)+1;
for(ll j = 1; j <= a[i]/2; j++){
if(i+(a[i]/2) == i+j + a[i-j]/2){
k = min(k, j);
}
if(i+(a[i]/2) < i+j + a[i-j]/2){
a[i+j] = (i+(a[i]/2))-(i+j);
a[i+j]*=2; a[i+j]++;
}else a[i+j] = a[i-j];
}i+=k;
}
ll res = 0;
for(ll i = 1; i < 2*n; i++){
res = max(res, a[i]/2+1);
}cout << "! " << res << endl; fflush(stdout);
}
int main(){
ios::sync_with_stdio(false); cin.tie(nullptr);
ll t=1; //cin >> t;
for(int i = 1; i <= t; i++){
solve();
}
}
