#include <bits/stdc++.h>
using namespace std;
int main() {
	int n,j,k,i,z;
	cin>>n;
	cout<<"? 1 "<<n<<"\n";
	cin>>z;
	int lo=1,hi=n,mid,ans;
	if(z==1)lo=2;
	else if(z==n)hi=n-1;
	else{
		cout<<"? 1 "<<z<<"\n";
		cin>>j;
		if(j==z){
			hi=z-1;
		}
		else lo=z+1;
	}
	if(hi<z){
	while(lo<=hi){
				mid=(hi+lo)/2;
				cout<<"? "<<mid<<" "<<z<<"\n";
				cin>>j;
				if(j==z){
					ans=mid;
					lo=mid+1;
				}
				else{
					hi=mid-1;
				}
			}
			cout<<"! "<<ans<<"\n";
	}
	else{
		while(lo<=hi){
				mid=(hi+lo)/2;
				cout<<"? "<<z<<" "<<mid<<"\n";
				cin>>j;
				if(j==z){
					ans=mid;
					hi=mid-1;
				}
				else{
					lo=mid+1;
				}
			}
			cout<<"! "<<ans<<"\n";	
	}
	return 0;
}