#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
int l = 1, r = 1000000001, mid, ans = -2;
int main() {
    while (true) {
        mid = (l + r) >> 1;
        printf("%d\n", mid);
        fflush(stdout);
        scanf("%d", &ans);

        if (ans == 0)
            break;
        if (ans > 0)
            r = mid;
        if (ans < 0)
            l = mid;
    }
}