import sys
input = sys.stdin.readline

Q=int(input())
S=set()
ans=[0]*30

for _ in range(Q):
    q=list(map(int,input().split()))
    if q[0]==1:
        x=q[1]
        if x not in S:
            S.add(x)
            for i in range(30):
                if (x>>i)&1:
                    ans[i]+=1
    elif q[0]==2:
        x=q[1]
        if x in S:
            S.discard(x)
            for i in range(30):
                if (x>>i)&1:
                    ans[i]-=1
    else:
        if len(S)==0:
            print(-1)
        else:
            x=0
            for a in ans[::-1]:
                x<<=1
                if a==len(S):
                    x+=1
            print(x)