1 /*
  2 ━━━━━┒ギリギリ♂ eye！
  3 ┓┏┓┏┓┃キリキリ♂ mind！
  4 ┛┗┛┗┛┃＼○／
  5 ┓┏┓┏┓┃ /
  6 ┛┗┛┗┛┃ノ)
  7 ┓┏┓┏┓┃
  8 ┛┗┛┗┛┃
  9 ┓┏┓┏┓┃
 10 ┛┗┛┗┛┃
 11 ┓┏┓┏┓┃
 12 ┛┗┛┗┛┃
 13 ┓┏┓┏┓┃
 14 ┃┃┃┃┃┃
 15 ┻┻┻┻┻┻
 16 */
 17 #include <algorithm>
 18 #include <iostream>
 19 #include <iomanip>
 20 #include <cstring>
 21 #include <climits>
 22 #include <complex>
 23 #include <cassert>
 24 #include <cstdio>
 25 #include <bitset>
 26 #include <vector>
 27 #include <deque>
 28 #include <queue>
 29 #include <stack>
 30 #include <ctime>
 31 #include <set>
 32 #include <map>
 33 #include <cmath>
 34 using namespace std;
 35 #define fr first
 36 #define sc second
 37 #define cl clear
 38 #define BUG puts("here!!!")
 39 #define W(a) while(a--)
 40 #define pb(a) push_back(a)
 41 #define Rint(a) scanf("%d", &a)
 42 #define Rll(a) scanf("%I64d", &a)
 43 #define Rs(a) scanf("%s", a)
 44 #define Cin(a) cin >> a
 45 #define FRead() freopen("in", "r", stdin)
 46 #define FWrite() freopen("out", "w", stdout)
 47 #define Rep(i, len) for(int i = 0; i < (len); i++)
 48 #define For(i, a, len) for(int i = (a); i < (len); i++)
 49 #define Cls(a) memset((a), 0, sizeof(a))
 50 #define Clr(a, x) memset((a), (x), sizeof(a))
 51 #define Full(a) memset((a), 0x7f7f7f, sizeof(a))
 52 #define lrt rt << 1
 53 #define rrt rt << 1 | 1
 54 #define pi 3.14159265359
 55 #define RT return
 56 #define lowbit(x) x & (-x)
 57 #define onenum(x) __builtin_popcount(x)
 58 typedef long long LL;
 59 typedef long double LD;
 60 typedef unsigned long long ULL;
 61 typedef pair<int, int> pii;
 62 typedef pair<string, int> psi;
 63 typedef pair<LL, LL> pll;
 64 typedef map<string, int> msi;
 65 typedef vector<int> vi;
 66 typedef vector<LL> vl;
 67 typedef vector<vl> vvl;
 68 typedef vector<bool> vb;
 69
 70 const int maxn = 6006000;
 71 typedef struct Node {
 72     int cnt;
 73     Node* next[2];
 74     Node() { cnt = 0; next[0] = next[1] = NULL; }
 75 }Node;
 76
 77 int mul(int x, int n) {
 78     int ret = 1;
 79     while(n) {
 80         if(n & 1) ret *= x;
 81         x *= x;
 82         n >>= 1;
 83     }
 84     return ret;
 85 }
 86
 87 Node memory[maxn];
 88 int mcnt;
 89 int q;
 90 Node* rt;
 91 char cmd[2];
 92 int n;
 93
 94 void insert(Node* p, int x) {
 95     for(int i = 31; i >= 0; i--) {
 96         int bit = x & (1 << i) ? 1 : 0;
 97         if(p->next[bit] == NULL) {
 98             p->next[bit] = &memory[mcnt++];
 99         }
100         p = p->next[bit];
101         p->cnt++;
102     }
103 }
104
105 void remove(Node* p, int x) {
106     for(int i = 31; i >= 0; i--) {
107         int bit = x & (1 << i) ? 1 : 0;
108         p = p->next[bit];
109         p->cnt--;
110     }
111 }
112
113 int query(Node* p, int x) {
114     int ret = 0;
115     for(int i = 31; i >= 0; i--) {
116         int bit = x & (1 << i) ? 0 : 1;
117         if(p->next[bit] && p->next[bit]->cnt >= 1) {
118             ret += mul(2, i);
119             p = p->next[bit];
120         }
121         else p = p->next[bit^1];
122     }
123     return ret;
124 }
125
126 int main() {
127 //    FRead();
128     while(~Rint(q)) {
129         Cls(memory); mcnt = 0;
130         rt = &memory[mcnt++];
131         insert(rt, 0);
132         W(q) {
133             Rs(cmd); Rint(n);
134             if(cmd[0] == '+') insert(rt, n);
135             else if(cmd[0] == '-') remove(rt, n);
136             else if(cmd[0] == '?') printf("%d\n", query(rt, n));
137         }
138     }
139     RT 0;
140 }