D. Vasiliy's Multiset

#include <bits/stdc++.h>

using namespace std;

long long getMaxXor(long long);
void addNewNum(long long);
void delOldNum(long long);
struct Trie;
Trie *newNode();

struct Trie{
    int cnt;
    Trie *next[2];
}*root = newNode();

Trie *newNode(){
    Trie *node;
    node = new Trie;
    node -> cnt = 0;
    node -> next[0] = node -> next[1] = NULL;
    return node;
}

long long getMaxXor(long long x){
    int Max = 0;
    Trie *Cur = root;
    for(int i=31 ; i>=0 ; i--){
        int T = x & (1 << i);
        bool idx = T ? 0 : 1;

        if(Cur -> next[idx] == NULL){
            if(Cur -> next[!idx] != NULL)
                idx = !idx;
            else if(Cur -> next[!idx] == NULL)
                return 0;
        }

        Cur = Cur -> next[idx];
        if(idx)
            Max |= ( 1 << i );
    }
    return Max;
}

void addNewNum(long long x){
    Trie *Cur = root;
    for(int i=31 ; i>=0 ; i--){
        int T = x & (1 << i);
        bool idx = T ? 1 : 0;
        if(Cur -> next[idx] == NULL){
            Cur -> next[idx] = newNode();
        }
        Cur = Cur -> next[idx];
        Cur -> cnt++;
        //cout << "new " << idx << ' ' << Cur -> cnt << ' ' << i << endl;
    }
}

void delOldNum(long long x){
    Trie *Cur = root;
    for(int i=31 ; i>=0 ; i--){
        int T = x & (1 << i);
        bool idx = T ? 1 : 0;

        Cur -> next[idx] -> cnt --;
        if(Cur -> next[idx] -> cnt == 0){
            Cur -> next[idx] = NULL;
            break;
        }else{
            Cur = Cur -> next[idx];
        }
    }
}

int main()
{
    int Q; cin >> Q;
    while(Q--){
        char ch;
        long long x;

        cin >> ch >> x;
        switch(ch){
            case '+':{
                addNewNum(x);
                }break;
            case '-':{
                delOldNum(x);
                }break;
            case '?':{
                long long Max = getMaxXor(x);
                //cout << x << " asd " << Max << endl;
                cout << (Max^x) << endl;
                }break;
        }
    }
    return 0;
}
/*
4
? 1
+ 1
+ 4
? 5
*/