#include <bits/stdc++.h>
using namespace std;
int ra() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
map<int, int> mp;
int a[35], q;
long long ans;
void orz(int x) {
  for (int i = 30; i >= 1; i--) a[30 - i + 1] = (x >> i - 1) & 1;
}
void add(int x, int num, int d) {
  if (d > 30) return;
  if (a[d] == 1) {
    mp[num << 1 | 1]++;
    add(x, num << 1 | 1, d + 1);
  } else {
    mp[num << 1]++;
    add(x, num << 1, d + 1);
  }
}
void del(int x, int num, int d) {
  if (d > 30) return;
  if (a[d] == 1)
    mp[num << 1 | 1]--, del(x, num << 1 | 1, d + 1);
  else
    mp[num << 1]--, del(x, num << 1, d + 1);
}
void ask(int x, int num, int d) {
  if (d > 30) return;
  if (a[d] == 1) {
    if (mp[num << 1] != 0) {
      ans += (long long)1 << (30 - d);
      ask(x, num << 1, d + 1);
    } else
      ask(x, num << 1 | 1, d + 1);
  } else {
    if (mp[num << 1 | 1] != 0) {
      ans += (long long)1 << (30 - d);
      ask(x, num << 1 | 1, d + 1);
    } else
      ask(x, num << 1, d + 1);
  }
}
int main() {
  q = ra();
  add(0, 1, 1);
  for (int i = 1; i <= q; i++) {
    char ch[2];
    int x;
    scanf("%s", &ch);
    x = ra();
    orz(x);
    if (ch[0] == '-') del(x, 1, 1);
    if (ch[0] == '+') add(x, 1, 1);
    if (ch[0] == '?') {
      ans = 0;
      ask(x, 1, 1);
      printf("%lld\n", ans);
    }
  }
  return 0;
}
