#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int ok = 1, ng = 1e9+1;
    auto f = [](int y) {
        cout << y << endl; cout.flush();
        int b; cin >> b;
        return b;
    };
    while(ng - ok > 1) {
        int mid = (ng + ok) / 2;
        (f(mid) ? ok : ng) = mid;
    }
    cout << ok << endl;
}