#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
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;
}
void solve() {
	long long n; cin >> n;
	long long l = floor_sqrt((n >> 30) << 30) - 5;
	long long r = floor_sqrt(((n >> 30)+1) << 30) + 5;
	for (long long i = l; i < r; ++i) {
		if (i < 0)continue;
		if (i * i <= (n^i) && (n^i) < (i + 1) * (i + 1)) {
			cout << (n^i) << endl;
			return;
		}
	}
	cout << -1 << endl;
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int t; cin >> t;
	while (t--)solve();
	return 0;
}