#include <iostream>
#include <cstdio>

int main() {
    int low = 1, high = 1000000000;
    int guess = (low + high) / 2;
    int result;

    while (true) {
        std::cout << guess << std::endl;
        fflush(stdout);

        std::cin >> result;

        if (result == 0) {
            break;
        } else if (result == 1) {
            high = guess - 1;
        } else if (result == -1) {
            low = guess + 1;
        }

        guess = (low + high) / 2;
    }

    return 0;
}