a = [[0,0] for _ in range(30)]; s = set()
for _ in range(int(input())):
    q = list(map(int,input().split()))
    if q[0]==1:
        x = q[1]
        if x in s: continue
        for i in range(30): a[i][x>>i&1] += 1
        s.add(x)
    if q[0]==2:
        x = q[1]
        if x not in s: continue
        for i in range(30): a[i][x>>i&1] -= 1
        s.remove(x)
    if q[0]==3:
        ans = 0
        for i,(p,q) in enumerate(a):
            if not p and q: ans |= 1<<i
        print(ans if s else -1)