1672E - notepadexe - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
const int W = 1e9;
const long long INF = 1e18;
int main(){
	long long n, poc=1, kon=W, mid, h;
	long long out=INF;
	cin >> n;
	while(poc<kon){
		mid=(poc+kon)/2;
		cout<<"? "<< mid << '\n';
		cout.flush();
		cin >> h;
		if(h==1) kon=mid;
		else poc=mid+1;
	}
	for(long long i=1; i<=n; i++){
		cout << "? "<< poc/i << '\n';
		cout.flush();
		cin >> h;
		if(h) out=min(out, (poc/i)*h);
	}
	cout << "! " << out;
	return 0;
}