#include<bits/stdc++.h>
using namespace std;
#ifndef ONLINE_JUDGE
#define dbg(x...) do{cout << "\033[32;1m" << #x << "->" ; err(x);} while(0)
void err(){cout << "\033[39;0m" << endl;}
template<template<typename...> class T,typename t,typename... A>
void err(T<t> a,A... x){for (auto v:a) cout << v << ' '; err(x...);}
template<typename T,typename... A>
void err(T a,A... x){cout << a << ' '; err(x...);}
#else
#define dbg(...)
#endif
typedef long long ll;
typedef pair<int,int> pi;
typedef vector<int> vi;
template<class T> using vc=vector<T>;
template<class T> using vvc=vc<vc<T>>;
template<class T> void mkuni(vector<T>&v)
{
    sort(v.begin(),v.end());
    v.erase(unique(v.begin(),v.end()),v.end());
}
template<class T>
void print(T x,int suc=1)
{
    cout<<x;
    if(suc==1) cout<<'\n';
    else cout<<' ';
}
template<class T>
void print(const vector<T>&v,int suc=1)
{
    for(int i=0;i<v.size();i++)
        print(v[i],i==(int)(v.size())-1?suc:2);
}
int ask(int x) {
	cout << "? " << x << endl;
	int now;
	cin >> now;
	return now;
}
int main() {
 	int n;
	cin >> n;
	//vi a(n + 1);
	//for(int i = 1; i <= n; ++i) cin >> a[i];
	int L = 1, R = n;
	while(L < R) {
		int mid = L + R >> 1;
		int r = ask(mid + 1);
		int l = ask(mid);
		if(l < r) R = mid;
		else L = mid + 1;
	}
	cout << "! " << L << endl;
}