// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define int long long
// #define endl "\n"
#define fi first
#define se second
const int M=1203465797;
const int inf = 1e14;
const int LOG=18;
const int N=2e3+5;
int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r;
void solve(){
cin >> n;
int i=2;
int j=2;
int ans=1;
while (i<=n){
if (i-j+1<1){
i++;
continue;
}
cout << "? " << i-j+1 << " " << i << endl;
cin >> x;
if (x){
ans=max(ans,j);
j+=2;
}
else{
i++;
}
}
i=3;
j=3;
while (i<=n){
if (i-j+1<1){
i++;
continue;
}
cout << "? " << i-j+1 << " " << i << endl;
cin >> x;
if (x){
ans=max(ans,j);
j+=2;
}
else{
i++;
}
}
cout << "! ";
cout << ans << endl;
}
signed main()
{
// #ifndef ONLINE_JUDGE
// freopen("input.txt","r" ,stdin);
// freopen("output.txt","w",stdout);
// #endif
// ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
// cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE
cout << fixed << setprecision(9);
srand(time(0));
// int t=1;
// cin >> t;
for (int _=1;_<=t;_++){
solve();
q++;
}
}
