#include <iostream>
#include <vector>
#include <cassert>

using namespace std;
using ll = long long;

void solve() {
    ll n; cin >> n;
    ll firstrun = 0;
    ll b = 0;
    for (int i = 0; i < 60; i++) {
        if ((1LL<<i) & n) {
            b = (1LL << i);
        }
    }
    ll a = n ^ b;
    if (a > 0) {
        assert((a+b)^n == (a^(n+b)^n));
        cout << a << ' ' << endl;
    }
    else {
        cout << -1 << endl;
    }
}
int main() {
    int t; cin >> t; while(t--) solve();
}