import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.util.*; public class Main { void solve() throws IOException { int high = (int) 1e9 + 1; int low = 1; while (high - low > 1) { int mid = (high + low) / 2; out.println(mid); out.flush(); int n = ni(); if (n == 0) { high = mid; } else { low = mid; } } out.println(low); } String ns() throws IOException { while (!tok.hasMoreTokens()) { tok = new StringTokenizer(in.readLine(), " "); } return tok.nextToken(); } int ni() throws IOException { return Integer.parseInt(ns()); } long nl() throws IOException { return Long.parseLong(ns()); } double nd() throws IOException { return Double.parseDouble(ns()); } String[] nsa(int n) throws IOException { String[] res = new String[n]; for (int i = 0; i < n; i++) { res[i] = ns(); } return res; } int[] nia(int n) throws IOException { int[] res = new int[n]; for (int i = 0; i < n; i++) { res[i] = ni(); } return res; } long[] nla(int n) throws IOException { long[] res = new long[n]; for (int i = 0; i < n; i++) { res[i] = nl(); } return res; } class INA { int[][] a; INA(int n, int m) throws IOException { this(n, m, -1); } INA(int n, int m, int t) throws IOException { a = new int[m][n]; for (int i = 0; i < n; i++) { for (int j = 0; j < m; j++) { a[j][i] = ni() + t; } } } int[] get(int i) { return a[i - 1]; } } static BufferedReader in; static PrintWriter out; static StringTokenizer tok; public static void main(String[] args) throws IOException { in = new BufferedReader(new InputStreamReader(System.in)); out = new PrintWriter(System.out); tok = new StringTokenizer(""); Main main = new Main(); main.solve(); out.close(); } }