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")
#######################################################################

m = 30
q = ni()
p = [0] * m
from collections import defaultdict
k = 0
d = defaultdict(int)
for _ in range(q):
    que = na()
    if que[0] == 1:
        x = que[1]
        if d[x] == 0:
            d[x] = 1
            k += 1
            for i in range(m):
                if x >> i & 1 ^ 1:
                    p[i] += 1
    elif que[0] == 2:
        x = que[1]
        if d[x] == 1:
            d[x] = 0
            k-=1
            for i in range(m):
                if x >> i & 1 ^ 1:
                    p[i] -= 1
    else:
        if k == 0:
            print(-1)
            exit()
        s = 0
        for i in range(m):
            if p[i] == 0:
                s += 1<<i
        print(s)