/// #459
#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int > pii;
typedef long long int lld;
#define pi acos(-1)
#define fr(i,m,n) for(i=m;i<n;i++)
#define fu(i,m,n) for(i=m;i>=n;i--)
#define vec vector<lld>
#define pb push_back
#define pp pop_back()
#define ft first
#define sd second
#define all(v) v.begin(),v.end()
#define mom(ara) memset(ara,0,sizeof(ara));
#define m1m(ara) memset(ara,-1,sizeof(ara));
#define endl "\n"
#define eps 1.19209e-07
lld query(lld l,lld r)
{
	lld x;
	cout<<"? "<<l<<" "<<r<<endl;
	cout.flush();
	cin>>x;
	return x;
}
int main()
{ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
    lld i,j,k,a,b,c,x,y,z,n,m,ans,t;
    cin>>n;
    z=query(1,n);
    if(z!=1) x=query(1,z);
    else x=0;
    if(x==z)
    {
    	lld l=1,r=z-1;
    	while(l<r)
    	{
    		lld mid=(l+r)/2;
    		if(query(mid+1,z)==z)
    		{
    			l=mid+1;
    		}
    		else r=mid;
    	}
    	cout<<"! "<<l<<endl;
    	cout.flush();
    }
    else
    {
    	lld l=z+1,r=n;
    	while(l<r)
    	{
    		lld mid=(l+r)/2;
    		if(query(z,mid)==z)
    		{
    			r=mid;
    		}
    		else l=mid+1;
    	}
    	cout<<"! "<<l<<endl;
    	cout.flush();
    }
}