#include<bits/stdc++.h>
using namespace std;

int tag;

void solve(int l,int r,int lst)
{
	if(tag==1)
	{
		return;
	}
	int mid,x,y;
	mid=(l+r)>>1;
	if(l==r)
	{
		tag=1;
		cout<<"! "<<r;
		cout.flush();
		return;
	}
	
	cout<<"? "<<mid<<"\n";
	cout.flush();
	cin>>x;
	if(x==lst)
	{
		tag=1;
		cout<<"! "<<mid;
		cout.flush();
		return;
	}
	
	cout<<"? "<<r<<"\n";
	cout.flush();
	cin>>y;
	if(y==x)
	{
		tag=1;
		cout<<"! "<<r;
		cout.flush();
		return;
	}
	cout<<x<<" "<<y<<endl;
	if(x<y)
	{
		solve(l,max(l,mid-1),y);
	}
	else
	{
		solve(min(r-1,mid+1),r-1,y);
	}
	return;
}

int main()
{
	int n;
	cin>>n;
	tag=0;
	solve(1,n,0);
	
	return 0;
}