#include <bits/stdc++.h>
using namespace std;
inline char get_char();
const int N = 3e6 + 10;
int T, n, cnt = 1;
int c[40], trie[N][3];
int rec[N];
inline void change(long long x) {
  memset(c, 0, sizeof(c));
  int ct = 0;
  while (x) c[++ct] = x & 1, x >>= 1;
}
inline int reply() {
  int p = 1, s = 0;
  for (register int i = 33; i >= 1; i--) {
    int &k = c[i];
    s <<= 1;
    if (!trie[p][k ^ 1] or !rec[trie[p][k ^ 1]]) {
      if (trie[p][k] and rec[trie[p][k]])
        p = trie[p][k];
      else
        break;
    } else
      p = trie[p][k ^ 1], s |= 1;
  }
  return s;
}
inline void insert() {
  int p = 1;
  for (register int i = 33; i >= 1; i--) {
    int &k = c[i];
    if (!trie[p][k]) trie[p][k] = ++cnt;
    p = trie[p][k], rec[p]++;
  }
}
inline void _delete() {
  int p = 1;
  for (register int i = 33; i >= 1; i--) {
    int &k = c[i];
    if (!trie[p][k] or !rec[trie[p][k]]) return;
    p = trie[p][k];
    rec[p]--;
  }
}
int main() {
  scanf("%d", &n);
  insert();
  while (n--) {
    static char c;
    static int x;
    c = get_char();
    scanf("%d", &x);
    change(x);
    if (c == '?')
      printf("%d\n", reply());
    else if (c == '+')
      insert();
    else
      _delete();
  }
  return 0;
}
inline char get_char() {
  register char c = getchar();
  while (c != '+' and c != '-' and c != '?') c = getchar();
  return c;
}
