#include <bits/stdc++.h>
using namespace std;
const int Maxn = 200005;
struct node {
  node *first, *second;
  int cnt;
  node(node *a, node *b) {
    first = a;
    second = b;
    cnt = 0;
  }
};
node *root = new node(NULL, NULL);
void insert(node *x, int bits, int idx) {
  (x->cnt)++;
  if (idx == -1) return;
  if ((1 << idx) & bits) {
    if (x->second == NULL) x->second = new node(NULL, NULL);
    insert(x->second, bits, idx - 1);
  } else {
    if (x->first == NULL) x->first = new node(NULL, NULL);
    insert(x->first, bits, idx - 1);
  }
}
void update(node *x, int bits, int idx) {
  (x->cnt)--;
  if (idx == -1) return;
  if ((1 << idx) & bits) {
    update(x->second, bits, idx - 1);
  } else {
    update(x->first, bits, idx - 1);
  }
}
void query(node *t, int a, int idx, int &ans) {
  if (idx == -1) return;
  if ((1 << idx) & a) {
    if (t->first == NULL)
      query(t->second, a, idx - 1, ans);
    else if ((t->first)->cnt <= 0)
      query(t->second, a, idx - 1, ans);
    else {
      ans += (1 << idx);
      query(t->first, a, idx - 1, ans);
    }
  } else {
    if (t->second == NULL)
      query(t->first, a, idx - 1, ans);
    else if ((t->second)->cnt <= 0)
      query(t->first, a, idx - 1, ans);
    else {
      ans += (1 << idx);
      query(t->second, a, idx - 1, ans);
    }
  }
}
int a[Maxn];
char s[5];
unordered_map<int, int> m;
int main() {
  int n;
  scanf("%d", &n);
  insert(root, 0, 29);
  for (int i = 0; i < n; i++) {
    scanf("%s", s);
    scanf("%d", &a[i]);
    if (s[0] == '+') {
      m[a[i]]++;
      if (m[a[i]] == 1) {
        insert(root, a[i], 29);
      }
    } else if (s[0] == '-') {
      m[a[i]]--;
      if (m[a[i]] == 0) update(root, a[i], 29);
    } else {
      int ans = 0;
      query(root, a[i], 29, ans);
      printf("%d\n", ans);
    }
  }
  return 0;
}
