#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#include <random>

using namespace std;

using ll = long long;



int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll left = 1LL;
    ll right = 1000000000LL;

    while (right - left > 0)
    {
        ll mid = (left + right) / 2;

        cout << mid << endl;

        int r;
        cin >> r;
        if (r == 1)
        {
        	break;
            left = mid + 1;
        }
        else
        {
            right = mid;
        }
    }
}