#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
using ll = long long;

int main(void){
  int left=1, right=1e9;
  while(right-left>1){
    int mid=(left+right)/2;
    cout << mid << endl;
    int r; cin >> r;
    if(r!=0) return 0;
    right=mid;
  }
  return 0; 
}