x = int(input())
a = [{1:0,0:0} for i in range(32)]
s = set()
for i in range(x):
    t =list(map(int,input().split()))
    if t[0] == 1:
        if t[1] in s:
            continue
        else:
            s.add(t[1])
            b=bin(t[1])
            for i in range(31,-1,-1):
                if  i >= len(b)-2:
                    a[i][0] += 1
                    continue
                a[i][int(b[~i])] += 1
                
    elif t[0] == 2:
        if t[1] not in s:
            continue
        else:
            s.discard(t[1])
            b=bin(t[1])
            for i in range(31,-1,-1):
                if  i >= len(b)-2:
                    a[i][0] -= 1
                    continue
                a[i][int(b[~i])] -= 1
                
    else:
        if len(s) == 0:
            print(-1)
            continue
        aa=0
        for i in range(31):
            if a[i][1] >= 1 and a[i][0] == 0:
                aa += pow(2,i)
        print(aa)