#include <bits/stdc++.h>
using namespace std;

int l = 1, r = 1e9, k;

int main() {
    while (1) {
        int mid = l + r >> 1;
        printf("%d\n", mid);
        fflush(stdout);
        scanf("%d", &k);
        if (k == 0)
            return 0;
        if (k == 1)
            r = mid - 1;
        else
            l = mid + 1;
    }
    return 0;
}