#include using namespace std; typedef long long int ll; typedef pair P; typedef vector VI; typedef vector VVI; #define REP(i,n) for(int i=0;i<(n);i++) #define ALL(v) v.begin(),v.end() template bool chmax(T& x, const T& y){return (x bool chmin(T& x, const T& y){return (x>y)?(x=y,true):false;}; constexpr ll MOD=998244353; constexpr ll INF=2e18; int main(){ int n; cin >> n; int z; REP(i,n/2){ cout << "? " << i << " " << i+1 << endl; cin >> z; if(z==i){ cout << "! " << i+1 << endl; return 0; } if(z==i+1){ cout << "! " << i << endl; return 0; } } cout << "! " << n-1 << endl; return 0; }