Q = int(input())
A = set()
B0 = [0]*30
B1 = [0]*30
for _ in range(Q):
    qry = list(map(int,input().split()))
    if qry[0]==1:
        x = qry[1]
        if x not in A:
            A.add(x)
            for i in range(30):
                if (x>>i) & 1:
                    B1[i] += 1
                else:
                    B0[i] += 1
    elif qry[0]==2:
        x = qry[1]
        if x in A:
            A.remove(x)
            for i in range(30):
                if (x>>i) & 1:
                    B1[i] -= 1
                else:
                    B0[i] -= 1
    else:
        if len(A)==0:
            print(-1)
        else:
            y = 0
            for i in range(30):
                if B0[i]==0 and B1[i]>0:
                    y += 1<<i
            print(y)