#include <bits/stdc++.h>
using namespace std;
struct No {
  map<char, pair<No *, long long> > trans;
  bool word = false;
};
No *head;
No *makeNo() { return new No(); }
char comp(char x) { return (x == '0' ? '1' : '0'); }
string toBin(long long x) {
  string r;
  for (long long i = 32; i >= 0; i--) {
    r += ((bool)(x & (1ll << i)) + '0');
  }
  return r;
}
string toBinQuery(long long x) {
  string r = "";
  for (long long i = 32; i >= 0; i--) {
    if ((bool)(x & (1ll << i)))
      r += '0';
    else
      r += '1';
  }
  return r;
}
long long toInt(string x) {
  long long c = 0;
  for (long long i = 0; i < 33; i++) {
    if (x[i] == '1') c += (1ll << (32 - i));
  }
  return c;
}
void insert(string x) {
  No *aux = head;
  for (char c : x) {
    if (aux->trans[c].first) {
      aux->trans[c].second += 1;
    } else {
      aux->trans[c].first = makeNo();
      aux->trans[c].second = 1;
    }
    aux = aux->trans[c].first;
  }
  aux->word = true;
}
void del(string x) {
  No *aux = head;
  long long i = 0;
  for (char c : x) {
    if ((--(aux->trans[c].second)) == 0) {
      aux->trans[c].first = NULL;
      return;
    }
    aux = aux->trans[c].first;
  }
}
string query(string x) {
  No *aux = head;
  string r = "";
  for (char c : x) {
    if (aux->trans[c].first) {
      r += c;
      aux = aux->trans[c].first;
    } else {
      r += comp(c);
      aux = aux->trans[comp(c)].first;
    }
  }
  return r;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  head = makeNo();
  long long q;
  cin >> q;
  insert(toBin(0));
  while (q--) {
    char aux;
    long long y;
    cin >> aux >> y;
    if (aux == '+') {
      string x = toBin(y);
      insert(x);
    } else if (aux == '-') {
      string x = toBin(y);
      del(x);
    } else {
      string x = toBinQuery(y);
      long long r = toInt(query(x)) ^ y;
      cout << r << endl;
    }
  }
}
