#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
#include <chrono>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int32_t main(){
int n, ans=0, a;
cin>>n;
for (int i=1; i<=n; ++i)while (1){
if (i-ans/2<1||i+(ans+1)/2>n)break;
cout<<"? "<<i-ans/2<<" "<<i+(ans+1)/2<<endl;
cin>>a;
if (a){
++ans;
continue;
}
if (i-(ans+1)/2<1||i+ans/2+1>n)break;
cout<<"? "<<i-(ans+1)/2<<" "<<i+ans/2+1<<endl;
cin>>a;
if (a)ans+=2;
else break;
}
cout<<"! "<<ans;
}
