#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    long long gus = 1e9 / 2, l = 1, r = 1e9;
    cout << gus << endl;
    fflush(stdout);
    int chk;
    while (1) {
        cin >> chk;
        if (chk == 0) {
            return 0;
        } else if (chk == -1) {
            l = gus + 1;
            gus = (l + r) / 2;
            cout << gus << endl;
            fflush(stdout);
        } else {
            r = gus - 1;
            gus = (l + r) / 2;
            cout << gus << endl;
            fflush(stdout);
        }
    }
}