#include <bits/stdc++.h>
using namespace std;

#define      PSB         push_back
#define      MP          make_pair
#define      ll          long long
#define      FastIO      ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
constexpr ll mod = 1e9  + 7;
const ll N=3e6+5;
const ll INF =1e18;

int prefix_count;
bool check;
vector<ll> vv,v;

struct node {
    bool endmark;
    int count;
    node* next[2];
    node()
    {
        endmark = false;
        count=0;
        for (int i = 0; i < 2; i++)
            next[i] = NULL;
    }
} * root;
void insert(int len)
{
    node* curr = root;
    int kount=0;
    for (int i = 0; i < len; i++) {
        int id = v[i];
        if (curr->next[id] == NULL)
            curr->next[id] = new node();
        curr = curr->next[id];
        ++ curr->count ; // count no of words with prefix till  curr
    }
    //curr->endmark = true;
}
void search(int len)
{
    node* curr = root;
    vv.clear();
    for (int i = 0; i < len; i++) {
        int id = (v[i]^1LL);
        if (curr->next[id] == NULL)
            id= (id ^ 1LL);
        curr = curr->next[id];
        if(id==v[i]) vv.PSB(0);
        else vv.PSB(1);
    }
    reverse(vv.begin(),vv.end());
    ll ct=1,ans=0;
    for(ll i=0;i<vv.size();i++){
      ans+=ct*vv[i];
      ct*=2LL;
    }
    cout<<ans<<endl;
    //if(curr->endmark) check= true;
    //prefix_count= curr->count; // count no of prefix in the trie for str
    //return curr->endmark;  //full word tai actually ase kina check kore
    //return true;  // eta krle prefix hishabe paile true bolbe
}
void del_full_trie(node* cur)
{
    for (int i = 0; i < 2; i++)
        if (cur->next[i])
            del_full_trie(cur->next[i]);

    delete (cur);
}
void del(int len)
{
    node* curr = root;
    bool ck=false;
    for (int i = 0; i < len; i++) {
        int id = v[i],pre;
        if((curr->next[id])->count==1){
          curr->next[id]=NULL;
          curr = curr->next[id];
          del_full_trie(curr);
          break;
        }
        curr = curr->next[id];
        ll x= -- curr->count ; // count no of words with prefix till  curr
        //cout<<id<<' '<<x<<endl;
    }
}

int main()
{

    //first time trying trie
    root = new node();
    for(ll j=0;j<32;j++)
      v.PSB(0);
    insert(v.size());

    ll n; cin>>n;
    for(ll i=0;i<n;i++){
      char ch; ll x;
      cin>>ch>>x;
      v.clear();
      for(ll j=0;j<32;j++){
        if(x%2) v.PSB(1);
        else v.PSB(0);
        x>>=1;
      }
      reverse(v.begin(),v.end());
      if(ch=='+') insert(v.size());
      else if(ch=='-') del(v.size());
      else search(v.size());
    }
    del_full_trie(root); //killed the trie
    return 0;
}