import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

from math import isqrt

# s = isqrt(k)
# s^2 <= n^s < (s+1)^2

def naive(n):
    for s in range(1, 1000):
        if s * s <= n ^ s < (s + 1) * (s + 1):
            return n ^ s
    return -1

def solve(n):
    # n ^ s <= n + s
    # s * s - s <= n
    # (s + 1)** 2 > n ^ s >= n & s 
    for s in range(isqrt(n) + 1000, max(-1, isqrt(n) - 1000), -1):
        if s * s <= n ^ s < (s + 1) * (s + 1):
            return n ^ s
    return -1

for _ in range(ni()):
    n = ni()
    print(solve(n))