#include <map>
#include <ctime>
#include <cmath>
#include <queue>
#include <stack>
#include <vector>
#include <string>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#define spause() system("pause")
//#define scanf scanf_s

using namespace std;
typedef long long llong;
typedef unsigned long long ullong;
typedef pair<int, int> prdd;

const llong inf = 0x7fffffffffffffff;

int l = 1, r = 1000000001, ans = -2, mid;

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;
        else
            l = mid;
    }
    // spause();
    return 0;
}