#include <iostream>
#include <stdio.h>
using namespace std;
int main() {
    int ini = 500000000, input = 0, high = 1000000000, low = 0;
    do {
        printf("%d\n", ini);
        fflush(stdout);
        scanf("%d", &input);
        if (input == 0)
            return 0;
        if (input == 1) {
            high = ini;
            if (ini == (high + low) / 2)
                ini--;
            else
                ini = (high + low) / 2;
        }
        if (input == -1) {
            low = ini;
            if (ini == (high + low) / 2)
                ini++;
            else
                ini = (high + low) / 2;
        }
    } while (true);
    return 0;
}