R=range
I=input
for t in R(int(I())):
	N=int(I());x,l=0,31
	for d in R(31):
		c=N>>d&1
		if d>l+1and c<1:break
		elif(d>l)^c:l=d;x|=1<<d
	else:x=-1
	print(x)