#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define P pair<ll,ll>
#define pub push_back
#define pob pop_back
#define mp make_pair
#define nl '\n' //new line
#define mset multiset
#define lb lower_bound
#define rep(i,n) for(ll i=0;i<(ll)(n);++i)
template<typename T> bool chmin(T& a,T b){if(a>b){a=b;return true;}return false;}
template<typename T> bool chmax(T& a,T b){if(a<b){a=b;return true;}return false;}
const int num=10'000'09; //2*10^5+9
const int INF=1'000'000'000; //10^9

int main(){
    ll l=1,r=INF;
    ll q=0;
    while(q==0){
     ll m=(l+r)/2;
     cout<<m<<nl;
     cin>>q;
     if(q==0) r=m;
    }
}