#include "bits/stdc++.h"
#define int long long
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 998244353;

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int X; cin >> X;
	for (int i = max(0LL, X - 1000000); i <= X + 1000000; i++) {
		int cnt = 0;
		for (int j = 0; j < 62; j++) {
			if (i >> j & 1) {
				cnt++;
			}
		}
		if ((i ^ cnt) == X) {
			cout << i << endl; return 0;
		}
	}
	cout << -1 << endl;
	return 0;
}