/* LittleFall : Hello! */
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
inline int read();
const int M = 500016, MOD = 1000000007;

int save[M];
int main(void) {
#ifdef _LITTLEFALL_
    freopen("in.txt", "r", stdin);
#endif

    int lef = 1, rig = 1000000000;
    while (lef <= rig) {
        int mid = (lef + rig) >> 1;
        cout << mid << endl;
        int t;
        cin >> t;
        if (t == 0)
            exit(0);
        else if (t > 0)
            rig = mid - 1;
        else
            lef = mid + 1;
    }

    return 0;
}

inline int read() {
    int x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-')
            f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        x = x * 10 + ch - '0';
        ch = getchar();
    }
    return x * f;
}