#include <bits/stdc++.h>
#define int long long
using namespace std;
int hist_min, hist_max;
const int INF = 1LL << 60;
#ifndef LOCAL
bool qry(int x){
cout << "? " << x << endl;
bool r; cin >> r;
return r;
}
void answer(int x){
cout << "= " << x << endl;
exit(0);
}
#else
int prv = -INF, N, C;
int shift[100];
bool qry(int x){
hist_min = min(hist_min, x);
hist_max = max(hist_max, x);
cout << "Q " << x << ' ' << N << endl;
assert(1 <= x && x <= N);
if(prv == -INF) { prv = x; return 0; }
bool res = abs(x - prv) >= C; prv = x;
return res;
}
void answer(int x){
assert(x == C);
}
#endif
bool fake_qry(int x){
hist_min = min(hist_min, x);
hist_max = max(hist_max, x);
return false;
}
void fake_answer(int x){
return;
}
void fake_solve(int N){
int lo = 1, hi = N;
int prv = 1; fake_qry(prv);
bool forward = true;
while(lo < hi){
int mid = (lo + hi - 1) / 2;
int nxt = forward ? prv + mid : prv - mid;
forward ^= true;
if(fake_qry(nxt)){
hi = mid;
}else{
lo = mid + 1;
}
prv = nxt;
}
fake_answer(lo);
}
void solve(int N){
fake_solve(N);
int lo = 1, hi = N;
int prv = 2 - hist_min; qry(prv);
bool forward = true;
while(lo != hi){
int mid = (lo + hi - 1) / 2;
int nxt = forward ? prv + mid : prv - mid;
forward ^= true;
if(qry(nxt)){
hi = mid;
}else{
lo = mid + 1;
}
prv = nxt;
}
answer(lo);
}
int32_t main(){
#ifdef LOCAL
random_device rd;
mt19937 rng(rd());
const int MX = 2;
for(int t = 0; t < 1; t++){
hist_min = INF, hist_max = -INF;
N = rng() % MX + 1;
C = rng() % N + 1;
N = 2; C = 1;
solve(N);
shift[N] = max(shift[N], 1 - hist_min);
}
#else
hist_min = INF, hist_max = -INF;
int N; cin >> N;
solve(N);
#endif
}
