/* -*- coding: utf-8 -*-
 *
 * 3102.cc:  No.3102 floor sqrt xor - yukicoder
 */

#include<cstdio>
#include<cmath>
#include<algorithm>

using namespace std;

/* constant */

/* typedef */

using ll = long long;

/* global variables */

/* subroutines */

/* main */

int main() {
  int tn;
  scanf("%d", &tn);

  while (tn--) {
    ll n;
    scanf("%lld", &n);

    if (n == 0) { puts("0"); continue; }
    if (n == 1) { puts("-1"); continue; }

    ll x0 = (n >> 30) << 30, x1 = ((n >> 30) + 1) << 30;
    int s0 = sqrt(0.5 + x0), s1 = sqrt(0.5 + x1);

    ll k = -1;
    for (int s = s0; s <= s1; s++) {
      ll sk = n ^ s;
      if (sk >= (ll)s * s && sk < (ll)(s + 1) * (s + 1)) {
	k = sk; break;
      }
    }

    printf("%lld\n", k);
  }

  return 0;
}