#pragma GCC optimize("Ofast")

#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <class T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <class T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct io_setup {
	io_setup() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(15);
	}
} io_setup;

void solve() {
	int n;
	cin >> n;
	if (__builtin_popcount(n) == 1) {
		cout << "-1\n";
		return;
	}
	int ans = 0;
	rep(i, 0, 30) {
		if (n >> i & 1) {
			if (ans > 0) {
				break;
			}
			ans += 1 << i;
		} else if (ans > 0) ans += 1 << i;
	}
	cout << ans << '\n';
}

int main() {
	int t = 1;
	cin >> t;
	while (t--) solve();
}