#include <bits/stdc++.h>
using namespace std;
#define IOS                  \
    ios::sync_with_stdio(0); \
    cin.tie(0);              \
    cout.tie(0);
#define PB push_back
typedef long long ll;
#define mod 1000000007

map<pair<int, int>, int> qans;
int query(int l, int r)
{
    if (qans.count({l, r}))
    {
        return qans[{l, r}];
    }
    if (l == r)
    {
        return -1;
    }
    cout << "? " << l << " " << r << endl;
    int ans;
    cin >> ans;
    return qans[{l, r}] = ans;
}

void answer(int x)
{
    cout << "! " << x << endl;
    exit(0);
}

void solve()
{
    int n;
    cin >> n;
    int smx = query(1, n);
    int ans;
    if (smx == query(1, smx))
    {
        int L = 1, U = smx - 1;
        while (L <= U)
        {
            int m = (L + U) / 2;
            if (query(m, smx) == smx)
            {
                ans = m;
                L = m + 1;
            }
            else
            {
                U = m - 1;
            }
        }
    }
    else
    {
        int L = smx + 1, U = n;
        while (L <= U)
        {
            int m = (L + U) / 2;
            if (query(smx, m) == smx)
            {
                ans = m;
                U = m - 1;
            }
            else
            {
                L = m + 1;
            }
        }
    }
    answer(ans);
}

int main()
{
    IOS;
    solve();
    return 0;
}