// #include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll inf = (1LL << 61);
ll dx[4] = {0, 1, 0, -1};
ll dy[4] = {-1, 0, 1, 0};
#define rep(i, n) for (ll i = 0; i < (ll)(n); ++i)
#define REP(i, init, n) for (ll i = (ll)init; i < (ll)(n); ++i)
// ll op(ll a, ll b) { return max(a, b); }
// ll e() { return -inf; }

int main() {
  ll l = 0, r = 1'000'000'001;
  while (r - l > 1) {
    ll m = (l + r) / 2;
    cout << m << endl;
    flush(cout);
    ll res;
    cin >> res;
    if (res == -1) {
      return -1;
    }
    if (res == 1) {
      l = m;
      break;
    } else
      r = m;
  }
  cout << l << endl;
  flush(cout);
}