import math

def solve():
	n = int(input())
	lb = max(0, math.isqrt(((n >> 30) + 0) << 30) - 1)
	ub = math.isqrt(((n >> 30) + 1) << 30) + 1
	for i in range(lb, ub + 1):
		if i * i <= (n ^ i) < (i+1) * (i+1):
			print(n ^ i)
			return
	print(-1)


t = int(input())
for _ in range(t):
	solve()