q = int(input())
res = 1 << 30
seen = set()
D = [0 for _ in range(30)]
for _ in range(q):
    L = list(map(int, input().split()))
    if L[0] == 1:
        x = L[1]
        if x not in seen:
            seen.add(x)
            for i in range(30):
                D[i] += x % 2
                x //= 2
    elif L[0] == 2:
        x = L[1]
        if x in seen:
            seen.remove(x)
            for i in range(30):
                D[i] -= x % 2
                x //= 2
    else:
        if len(seen) == 0:
            print(-1)
            continue
        ans = 0
        num = len(seen)
        for i in range(30):
            if D[i] == num:
                ans += 1 << i
        print(ans)