#include<bits/stdc++.h>
using namespace std;

// [floor_sqrt(N)]
// 0 <= N <= 9e18
long long floor_sqrt(long long N) {
	long long ub = 3'000'000'001;
	long long lb = 0;
	while (ub - lb > 1) {
		long long t = (ub + lb) / 2;
		if (t * t <= N) lb = t;
		else ub = t;
	}
	return lb;
}

typedef long long ll;

void solve() {
	ll n; cin >> n;
	ll lb = floor_sqrt((n >> 30) << 30) - 5;
	ll ub = floor_sqrt(((n >> 30) + 1) << 30) + 5;
	for (ll x=lb; x<ub; x++) {
		if (x < 0) continue;
		if (x*x <= (n^x) && (n^x) < (x+1)*(x+1)) {
			cout << (n^x) << '\n';
			return;
		}
	}
	cout << -1 << '\n';
}

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