#include <cstdio>
#include <iostream>
using namespace std;
int l = 1, r = 1000000001, ans = -2, mid;

int main() {
    while (true) {
        mid = (l + r) >> 1;
        cout << mid << endl;
        fflush(stdout);
        cin >> ans;
        if (ans == 0)
            break;
        if (ans > 0)
            r = mid;
        else
            l = mid;
    }
    return 0;
}