#include <bits/stdc++.h>
using namespace std;
const int N = 200005;
int fen[N];
void add(int i, int val) {
  for (; i < N; i |= (i + 1)) fen[i] += val;
}
int sum(int i) {
  int s = 0;
  for (; i >= 0; i = (i & (i + 1)) - 1) s += fen[i];
  return s;
}
int main() {
  int Q;
  scanf("%d", &Q);
  vector<int> t(Q), a(Q), ts(Q);
  char buf[10];
  for (int i = 0; i < Q; ++i) {
    scanf("%s%d", buf, &a[i]);
    ts[i] = a[i];
    if (buf[0] == '-') t[i] = -1;
    if (buf[0] == '+') t[i] = 1;
  }
  add(0, 1);
  ts.push_back(0);
  sort(ts.begin(), ts.end());
  ts.resize(unique(ts.begin(), ts.end()) - ts.begin());
  for (int q = 0; q < Q; ++q) {
    int i = lower_bound(ts.begin(), ts.end(), a[q]) - ts.begin();
    if (t[q]) {
      add(i, t[q]);
    } else {
      int res = 0;
      for (int b = 30; b >= 0; --b) {
        int B = (1 << b);
        int l = res, r = res + B - 1;
        if (!(a[q] & B)) {
          l += B;
          r += B;
        }
        int ri = upper_bound(ts.begin(), ts.end(), r) - ts.begin();
        int li = lower_bound(ts.begin(), ts.end(), l) - ts.begin();
        if (sum(ri - 1) == sum(li - 1)) {
          res += (a[q] & B);
        } else {
          res += (B ^ (a[q] & B));
        }
      }
      printf("%d\n", a[q] ^ res);
    }
  }
  return 0;
}
