#include <bits/stdc++.h> #include <atcoder/all> #define OVERLOAD_REP(_1, _2, _3, name, ...) name #define REP1(i,n) for (auto i = std::decay_t<decltype(n)>{}; (i) != (n); ++(i)) #define REP2(i,l,r) for (auto i = (l); (i) != (r); ++(i)) #define rep(...) OVERLOAD_REP(__VA_ARGS__, REP2, REP1)(__VA_ARGS__) #define all(a) (a).begin(),(a).end() #define rall(a) (a).rbegin(),(a).rend() using namespace std; using namespace atcoder; using ll = long long; using ull = unsigned long long; using P = pair<int,int>; using LP = pair<long long,long long>; using SP = pair<string,string>; using vi = vector<int>; using vl = vector<long long>; using vs = vector<string>; using vc = vector<char>; using mint1 = modint1000000007; using mint9 = modint998244353; const int INF = 2e9; const long long LINF = 4e18; const int di[] = {0,1,0,-1,-1,1,-1,1}; const int dj[] = {1,0,-1,0,1,1,-1,-1}; template<class T> inline bool chmin(T& a, T b){if(a>b){a=b;return true;}return false;} template<class T> inline bool chmax(T& a, T b){if(a<b){a=b;return true;}return false;} void YesNo (bool ok , const string &s , const string &t) {if(ok) cout << s << endl; else cout << t << endl;} //-----def end-----// int main () { int n; cin >> n; for(int i = 0; i < n/2; i++) { int i2 = i*2; cout << "? " << i2 << " " << i2+1 << endl; int z; cin >> z; if(z == i2) { cout << "! " << i2+1 << endl; return 0; } if(z == i2+1) { cout << "! " << i2 << endl; return 0; } } cout << n-1 << endl; return 0; }