// Problem: C1. Guessing the Greatest (easy version)
// Contest: Codeforces - Codeforces Round #703 (Div. 2)
// URL: https://codeforces.com/contest/1486/problem/C1
// Memory Limit: 256 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
#define rep(i,x,y) for(auto i=(x);i<=(y);++i)
#define dep(i,x,y) for(auto i=(x);i>=(y);--i)
#define fr first
#define sc second
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,ll>pil;
typedef pair<int,int>pii;
typedef pair<ll,ll>pll;
const int N=1e6+10;
const int inf=1e9;
const int mo=998244353;
ll a[N];
int query(int l,int r){
    cout<<"? "<<l<<" "<<r<<endl;
    cout.flush();
    int x; cin>>x;
    return x;
}
int main(){
    //freopen("D:\\in.txt","r",stdin);
    //freopen("D:\\out.txt","w",stdout);
    int n; cin>>n;
	int p=query(1,n);
	int l=1,r=n,mid;
	if(p!=1&&p==query(1,p)){
		r=p;
		while(r-l>1){
			mid=l+r>>1;
			if(query(mid,p)==p) l=mid;
			else r=mid;  
		}
	}
	else{
		l=p;
		while(r-l>1){
			mid=l+r>>1;
			if(query(p,mid)==p) r=mid;
			else l=mid;  
		}
	}
	p=query(l,r);
	if(p==l) p=r;
	else p=l;
	cout<<"! "<<p<<endl;
    cout.flush();
    return 0;
}