#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define db double
#define ld long double
#define forr(i,a,n) for(int i=a;i<n;i++)
#define rep(i,n) forr(i,0,n)
#define repp(i,n) forr(i,1,n+1)
#define pb push_back
#define mp make_pair
#define vvi vector<vector<int> >
#define MAXN 0x3f3f3f3f
int ask(int l,int r){
	if(l==r)return 0;
	fflush(stdout);
	cout<<'?'<<' '<<l<<' '<<r<<endl;
	cin>>l;
	return l;
}
int main(){
	int n;
	cin>>n;
	int l=1,r=n,mid,pos;
	pos=ask(l,r);
	while(l<=r){
		if(l==r){
			cout<<'!'<<' '<<l;
			return 0;
		}
		mid=(l+r)/2;
		if(pos<=mid){
			if(mid<=1)l=mid+1;
			else if(ask(1,mid)==pos)r=mid;
				else l=mid+1;
		}
		else{
			if(mid+1>=n)r=mid;
			else if(ask(mid+1,n)==pos)l=mid+1;
				else r=mid;
		}
	}
	return 0;
}

