#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int main() {
    int left = 1, right = 1e9;
    while (left <= right) {
        int mid = (left + right) / 2;
        printf("%d\n", mid);
        fflush(stdout);
        int x;
        scanf("%d", &x);
        if (x == 0) {
            break;
        }
        if (x < 0) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }
    return 0;
}