#include <algorithm>
#include <array>
#include <vector>
#include <utility>
#include <iostream>
#include <cassert>
#include <set>
#include <random>
#include <climits>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
#define forn(i,n) for (int i = 0; i<n; i++)
#define forl(i,l,h) for (int i = l; i<h; i++)
#define el << '\n'
#define nl cout << '\n'
#define spc << ' '
#define pb push_back
#define all(x) x.begin(), x.end()
#define sz(x) (int) x.size()
#define fi first
#define se second
const int inf = 1000000000;
const ll inf2 = 2000000000000000000;

const int MAXN = 1000005;
ll hv[MAXN];
vector<pair<ll, int>> vti(MAXN);

void gr() {
    srand(238957);
    forn(i,MAXN) {
        hv[i] = (ll) INT_MAX * rand() + rand();
        vti[i] = {hv[i], i};
    }
    sort(all(vti));
}

void st() {
    int n; cin >> n;
    ll v = 0;
    forn(i,n) {
        int a; cin >> a;
        v ^= hv[a];
        if (v==0) cout << "0\n";
        else {
            auto temp = (*lower_bound(all(vti),make_pair(v,-1)));
            if (temp.fi == v) cout << temp.se el;
            else cout << -1 el;
        }
    }
    cout << v el;
}

void ed() {
    ll v; cin >> v;
    int n; cin >> n;
    forn(i,n) {
        int a; cin >> a;
        v ^= hv[a];
        if (v==0) cout << "0\n";
        else {
            auto temp = (*lower_bound(all(vti),make_pair(v,-1)));
            if (temp.fi == v) cout << temp.se el;
            else cout << -1 el;
        }
    }
}

int main() {
    cin.tie(NULL); ios_base::sync_with_stdio(false);
    gr();
    string s; cin >> s;
    if (s=="start") st();
    else ed();
}