// #include <bits/stdc++.h> #include <iostream> #include <cmath> #include <algorithm> #include <map> #include <unordered_map> #include <vector> #include <iomanip> #include <string> #include <queue> #include <set> #include <deque> using namespace std; #define int long long // #define endl "\n" #define fi first #define se second const int M=1203465797; const int inf = 1e14; const int LOG=18; const int N=2e3+5; int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r; void solve(){ cin >> n; int i=2; int j=2; int ans=1; while (i<=n){ if (i-j+1<1){ i++; continue; } cout << "? " << i-j+1 << " " << i << endl; cin >> x; if (x){ ans=max(ans,j); j+=2; } else{ i++; } } i=3; j=3; while (i<=n){ if (i-j+1<1){ i++; continue; } cout << "? " << i-j+1 << " " << i << endl; cin >> x; if (x){ ans=max(ans,j); j+=2; } else{ i++; } } cout << ans << endl; } signed main() { // #ifndef ONLINE_JUDGE // freopen("input.txt","r" ,stdin); // freopen("output.txt","w",stdout); // #endif // ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE // cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE cout << fixed << setprecision(9); srand(time(0)); // int t=1; // cin >> t; for (int _=1;_<=t;_++){ solve(); q++; } }