freq = [0] * 30
dic = set()
Q = int(input())
cnt = 0
for _ in range(Q):
    query = input().split()
    if query[0] == "1":
        x = int(query[1])
        if x not in dic:
            dic.add(x)
            for i in range(30):
                if x & (1 << i):
                    freq[i] += 1
    elif query[0] == "2":
        x = int(query[1])
        if x in dic:
            dic.remove(x)
            for i in range(30):
                if x & (1 << i):
                    freq[i] -= 1
    else:
        x = len(dic)
        if x == 0:
            print(-1)
            continue
        ans = 0
        for i in range(30):
            if freq[i] == x:
                ans += 1 << i
        print(ans)