#include<iostream>
#include<vector>
#include<cassert>
using namespace std;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int N=1e9;
	while(true)
	{
		int x=(N+1)/2;
		cout<<x<<endl;
		int r;cin>>r;
		if(r==1)break;
		N=x-1;
	}
}