#include <bits/stdc++.h>
using namespace std;
long long n, q, v[6000005][2], su[6000005], raod, ans, x, tt;
string second;
void add(long long x, long long sz) {
  su[x]++;
  if (sz == 33) return;
  long long t = second[sz] - '0';
  if (v[x][t] == 0) v[x][t] = raod, raod++;
  add(v[x][t], sz + 1);
}
void remove(long long x, long long sz) {
  su[x]--;
  if (sz == 33) return;
  long long t = second[sz] - '0';
  remove(v[x][t], sz + 1);
}
void qu(long long x, long long sz) {
  if (sz == 33) return;
  long long t = second[sz] - '0';
  if (t == 0 && su[v[x][1]]) {
    ans += 1 << (32 - sz);
    qu(v[x][1], sz + 1);
  } else if (t == 0) {
    qu(v[x][0], sz + 1);
  } else if (t == 1 && su[v[x][0]]) {
    ans += 1 << (32 - sz);
    qu(v[x][0], sz + 1);
  } else {
    qu(v[x][1], sz + 1);
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin >> q;
  raod = 2;
  while (q--) {
    char c;
    cin >> c;
    cin >> x;
    long long xx = x;
    second = "";
    while (x) {
      second += (x % 2) + '0';
      x /= 2;
    }
    while ((int)second.size() != 33) second += '0';
    reverse(second.begin(), second.end());
    if (c == '+') add(1, 0), tt++;
    if (c == '-') remove(1, 0), tt--;
    if (c == '?') {
      ans = 0;
      qu(1, 0);
      cout << max(ans, xx) << endl;
    }
  }
  return 0;
}
