#include <bits/stdc++.h> using namespace std; signed main(){ // ios_base::sync_with_stdio(false); // cin.tie(NULL); int n; cin >> n; int l = 1, r = n; while(l <= r){ int md = (l + r) / 2; cout << "? " << md << endl; int t; cin >> t; if(t == -1){ l = md + 1; }else if(t == 1){ r = md - 1; }else{ cout << "= " << md << endl; return 0; } } }