#include <bits/stdc++.h>
using namespace std;
struct node {
  node* next[2];
  int child;
  node() {
    child = 0;
    next[1] = next[0] = 0;
  }
} * root;
void Insert(int tmp) {
  node* curr = root;
  root->child += 1;
  for (int i = 31; i >= 0; i--) {
    bool val = (tmp & (1 << i));
    if (curr->next[val] == 0) {
      curr->next[val] = new node();
    }
    curr = curr->next[val];
    curr->child += 1;
  }
  curr = root;
  for (int i = 31; i >= 0; i--) {
    bool val = (tmp & (1 << i));
    curr = curr->next[val];
  }
}
void Delete(int tmp) {
  node* curr = root;
  root->child -= 1;
  for (int i = 31; i >= 0; i--) {
    bool val = (tmp & (1 << i));
    curr = curr->next[val];
    curr->child -= 1;
  }
}
int Query(int tmp) {
  node* curr = root;
  int ans = 0;
  for (int i = 31; i >= 0; i--) {
    ans <<= 1;
    int bit = !(tmp & (1 << i));
    if (curr->next[bit] == 0 || curr->next[bit]->child == 0) bit ^= 1;
    curr = curr->next[bit];
    ans |= bit;
  }
  return (ans ^ tmp);
}
int q;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  root = new node();
  Insert(0);
  cin >> q;
  while (q--) {
    string s, s1;
    int tmp;
    cin >> s >> tmp;
    if (s == "+")
      Insert(tmp);
    else if (s == "-")
      Delete(tmp);
    else
      cout << Query(tmp) << '\n';
  }
  cout << endl;
  return 0;
}
