#include <bits/stdc++.h>
using namespace std;
typedef struct node {
  struct node* b[3];
  int flag[3];
} node;
node* root;
vector<int> ans;
int bit[32], bit_n[32];
void calc(int u) {
  memset(bit_n, 0, sizeof(bit_n));
  memset(bit, 0, sizeof(bit));
  int j = 0, num;
  for (num = u; num > 0; num = num / 2) bit_n[j++] = num % 2;
  for (int i = 0; i < 32; i++) bit[i] = bit_n[31 - i];
}
void insert(int u) {
  node* head;
  head = root;
  calc(u);
  for (int i = 0; i < 32; i++) {
    if (head->b[bit[i]] == NULL) {
      node* temp;
      temp = (node*)malloc(sizeof(node));
      for (int j = 0; j < 3; j++) temp->b[j] = NULL, temp->flag[j] = 0;
      head->b[bit[i]] = temp;
    }
    head->flag[bit[i]]++;
    head = head->b[bit[i]];
  }
  return;
}
void del(int u) {
  node* head;
  head = root;
  calc(u);
  for (int i = 0; i < 32; i++) {
    head->flag[bit[i]]--;
    head = head->b[bit[i]];
  }
  return;
}
void search(int u) {
  calc(u);
  node* head;
  head = root;
  for (int i = 0; i < 32; i++) {
    if (bit[i] == 1) {
      if (head->flag[0])
        ans.push_back(1), head = head->b[0];
      else
        ans.push_back(0), head = head->b[1];
    } else {
      if (head->flag[1])
        ans.push_back(1), head = head->b[1];
      else
        ans.push_back(0), head = head->b[0];
    }
  }
}
int main() {
  root = (node*)malloc(sizeof(node));
  for (int i = 0; i < 3; i++) root->b[i] = NULL, root->flag[i] = 0;
  int n;
  cin >> n;
  insert(0);
  char a;
  int num;
  for (int i = 0; i < n; i++) {
    int calc = 0;
    cin >> a >> num;
    if (a == '+')
      insert(num);
    else if (a == '-')
      del(num);
    else {
      ans.clear();
      search(num);
      for (int i = 0; i < ans.size(); i++) calc += (pow(2, 31 - i) * ans[i]);
      cout << calc << "\n";
    }
  }
  return 0;
}
