package main

import . "fmt"
import . "os"
import bf "bufio"

func main() {
	rd := bf.NewReader(Stdin)
	var q int
	Fscan(rd,&q)
	s := map[int]bool{}
	bits := make([]int, 31)
	for i := 0; i < q; i++ {
		var cmd, x int
		Fscan(rd, &cmd)
		switch cmd {
			case 1:
				Fscan(rd, &x)
				if !s[x] {
					s[x] = true
					for i := 0; i <= 30; i++ {
						bits[i] += (x>>i)&1
					}
				} 
			case 2:
				Fscan(rd, &x)
				if s[x] {
					delete(s, x)
					for i := 0; i <= 30; i++ {
						bits[i] -= (x>>i)&1
					}
				}
			case 3:
				if n := len(s); n == 0 {
					Println(-1)
				} else {
					for i := 0; i <= 30; i++ {
						if bits[i] == n {
							x |= 1 << i
						}
					}
					Println(x)
				}
		}
	}
}