#include <iostream>
#define int long long
using namespace std;

signed main() {
	int T;
	cin >> T;
	while (T--) {
		int n;
		cin >> n;

		int ok = 0, ng = (1LL << 30), mid;
		while (ng - ok >= 2) {
			mid = (ok + ng) / 2;
			if (mid * mid <= n) ok = mid;
			else ng = mid;
		}

		bool find = false;
		for (int i = -10000; i <= 10000; i++) {
			int sqK = ok + i;
			if (sqK < 0) continue;
			int k = n ^ sqK;
			if (sqK * sqK <= k && k < (sqK + 1) * (sqK + 1)) {
				cout << k << endl;
				find = true;
				break;
			}
		}
		if (!find) {
			cout << -1 << endl;
		}
	}
	return 0;
}