#include <bits/stdc++.h>
using namespace std;
typedef struct data {
  data* bit[2];
  long long cnt = 0;
} trie;
trie* head;
void insert(long long x) {
  trie* node = head;
  for (long long i = 30; i >= 0; i--) {
    long long curbit = (x >> i) & 1;
    if (node->bit[curbit] == NULL) {
      node->bit[curbit] = new trie();
    }
    node = node->bit[curbit];
    node->cnt++;
  }
}
void remove(long long x) {
  trie* node = head;
  for (long long i = 30; i >= 0; i--) {
    long long curbit = (x >> i) & 1;
    node = node->bit[curbit];
    node->cnt--;
  }
}
long long maxxor(long long x) {
  trie* node = head;
  long long ans = 0;
  for (long long i = 30; i >= 0; i--) {
    long long curbit = (x >> i) & 1;
    if (node->bit[curbit ^ 1] != NULL && node->bit[curbit ^ 1]->cnt > 0) {
      ans += (1LL << i);
      node = node->bit[curbit ^ 1];
    } else
      node = node->bit[curbit];
  }
  return ans;
}
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  head = new trie();
  insert(0);
  long long q;
  cin >> q;
  while (q--) {
    char ch;
    cin >> ch;
    long long x;
    cin >> x;
    if (ch == '+')
      insert(x);
    else if (ch == '-')
      remove(x);
    else
      cout << maxxor(x) << "\n";
  }
  return 0;
}
