Q=int(input())
s=set()
res=[0]*30

for i in range(Q):
 q=list(map(int,input().split()))
 if q[0]==1:
  if q[1] not in s:
   s.add(q[1])
   for j in range(30):
    if (q[1]>>j)&1:
     res[j]+=1
 elif q[0]==2:
  if q[1] in s:
   s.discard(q[1])
   for j in range(30):
    if (q[1]>>j)&1:
     res[j]-=1
 else:
  if len(s)==0:
   print(-1)
  else:
   x=0
   for a in res[::-1]:
    x<<=1
    if a==len(s):
     x+=1
   print(x)