#include <bits/stdc++.h>
using namespace std;

int main () {
  int left = 1;
  int right = 1 << 30;
  
  while(true){
    cout << (left + right) / 2 << endl;
    
    int ans;
    cin >> ans;
    
    if(ans == 0){
      right = (left + right) / 2;
    } else {
      return 0;
    }
  }
}