#include <bits/stdc++.h>
#define pb push
#define speed ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector <ll> vll;
typedef pair<ll,ll> pll;
typedef vector <pair<ll,ll>> vpll;
typedef vector <vll> vvll;
ll n;

int get(int x,int y)
{
    int val;
    cout<<"? "<<x<<" "<<y<<endl;
    cin>>val;
    return val;
}

int main()
{
    speed;
    cin>>n;
    ll l,h,m,midx,i;
    midx=get(1,n);
    
    if(midx>1 && get(1,midx)==midx)
    {
        l=1;
        h=midx-1;
        
        while(l<h)
        {
            m=(l+h+1)/2;
            i=get(m,midx);
            if(i==midx)
                l=m;
            else 
                h=m-1;
        }
        cout<<"! "<<l<<endl;
    }
    else
    {
        l=midx+1;
        h=n;
        
        while(l<h)
        {
            m=(l+h)/2;
            i=get(midx,m);
            if(i!=midx)
                l=m+1;
            else
                h=m;
        }
        cout<<"! "<<l<<endl;
    }
    return 0;
}