import sys
input = sys.stdin.readline
from collections import *

flag = defaultdict(int)
cnt = 0
bit = [0]*30

for _ in range(int(input())):
    qs = list(map(int, input().split()))
    
    if qs[0]==1:
        x = qs[1]
        
        if flag[x]==0:
            flag[x] = 1
            cnt += 1
            
            for b in range(30):
                if (x>>b)&1:
                    bit[b] += 1
    elif qs[0]==2:
        x = qs[1]
        
        if flag[x]==1:
            flag[x] = 0
            cnt -= 1
            
            for b in range(30):
                if (x>>b)&1:
                    bit[b] -= 1
    else:
        if cnt==0:
            print(-1)
        else:
            ans = 0
            
            for b in range(30):
                if bit[b]==cnt:
                    ans += 1<<b
                
            print(ans)