/* -*- coding: utf-8 -*-
 *
 * 3276.cc:  No.3276 Make Smaller Popcount - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

const int BN = 30;

/* typedef */

/* global variables */

int bs[BN];

/* subroutines */

/* main */

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

  while (tn--) {
    int n;
    scanf("%d", &n);

    int k = 0;
    for (int i = 0; i < BN; i++)
      if ((n >> i) & 1) bs[k++] = i;

    if (k >= 2) {
      int x = (1 << bs[1]) - (1 << bs[0]);
      printf("%d\n", x);
    }
    else
      puts("-1");
  }

  return 0;
}