#include #include using namespace std; using namespace atcoder; typedef int64_t lint; #define rep(i, n) for(int i=0; i; using vvi = vector>; template inline void vin(vector& v) { rep(i, v.size()) cin >> v.at(i); } template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } template inline void drop(T x) { cout << x << endl; exit(0); } template void vout(vector v) { rep(i, v.size()) { cout << v.at(i) << ' '; } cout << endl; } constexpr lint LINF = LLONG_MAX/2; int main() { lint N; cin >> N; lint a=0, b=0, c=0, x, y, z; rep(i, N/2) { cout << "? " << i*2 << ' ' << i*2+1 << endl; cin >> x; if (x == i*2) { cout << "! " << i*2+1 << endl; exit(0); } else if (x == i*2+1) { cout << "! " << i*2 << endl; exit(0); } } cout << "! " << N-1 << endl; }