G 76

/*

 ∧＿∧
( ･ω･｡)つ━☆・*。
⊂　 ノ 　　　・゜
しーＪ　　 Accepted

*/



// #pragma GCC optimize("O3")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define ll long long
#define all(x) begin(x), end(x)
#define x first
#define y second
#define int long long

using namespace std;
using namespace __gnu_pbds;

typedef long double ld;
template<typename T>
using kawaii_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const ld PI = atan2(0, -1);

void seriy() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cout << fixed << setprecision(14);
    #ifdef _offline
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif
}

const int MAXN = 3e5 + 100;
const int MAXM = 600;
const int INF = 1e18 + 7;
const int BASE = 47;
const int MOD = 1e9 + 7;
const int MAXLOG = 51;
const ld EPS = 1e-6;

vector<int> a_int;
vector<string> a;
int n;
string b;
int b_int, ans_int = -1;

int dec(string s) {
    int sum = 0;
    for(int i = 0; i < s.size(); i++) {
        if(s[i] == '1') {
            sum += (1ll << i);
        }
    }
    return sum;
}

string bin(int a) {
    string t = "";
    bool f = 0;
    for(int i = MAXLOG; i >= 0; i--) {
        if(a >= (1ll << i)) {
            f = 1;
            t += '1';
            a -= (1ll << i);
        }
        else if(f) {
            t += '0';
        }
    }
    if(t.size() == 0) t = "0";
    return t;
}

void add(string &s, int pw) {
    int p = pw;
    while(s.size() - 1 < p) {
        s += '0';
    }
    while(p < s.size() && s[p] == '1') {
        s[p] = '0';
        p++;
    }
    // cerr << s << " " << p << '\n';
    if(p < s.size()) {
        s[p] = '1';
    }
    else {
        s += '1';
    }
}

void subtract(string &s, int pw) {
    int p = pw;
    while(p < s.size() && s[p] == '0') {
        s[p] = '1';
        p++;
    }
    s[p] = '0';
}

string xor1(string &a, string &b) {
    string ans;
    ans.resize(max(a.size(), b.size()), '0');
    for(int i = 0; i < max(a.size(), b.size()); i++) {
        if(i < min(a.size(), b.size())) {

        }
        else if(a.size() < b.size()) {
            a += '0';
        }
        else if(a.size() > b.size()){
            b += '0';
        }
        ans[i] = ((a[i] == b[i]) ? '0' : '1');
    }
    return ans;
}

string ans = "-1";

void solve(string cur, int pw, string cur_sum) {
    if(pw > b.size()) {
        string kek = cur_sum;
        while(kek.back() == '0') {
            kek.pop_back();
        }
        if(!kek.size()) {
            kek = "0";
        }
        // cerr << cur << " " << cur_sum << '\n';
        if(kek == b) {
            ans = cur;
        }
        return;
    }
    string kek = cur_sum;
    while(kek.back() == '0') {
        kek.pop_back();
    }
    if(!kek.size()) {
        kek = "0";
    }
    while(cur_sum.size() < b.size()) {
        cur_sum += '0';
    }
    // cerr << cur << " " << ?cur_sum << " " << b << " " << kek << '\n';
    if((pw < b.size() && pw < cur_sum.size() && cur_sum[pw] == b[pw]) || kek == b) {
        solve(cur, pw + 1, cur_sum);
    }
    if(ans != "-1") {
        return;
    }
    string sum = "0";
    for(int i = 0; i < n; i++) {
        add(a[i], pw);
        sum = xor1(sum, a[i]);
    }
    string sum_c = sum;
    while(sum_c.back() == '0') {
        sum_c.pop_back();
    }
    if(sum_c.size() == 0) {
        sum_c = "0";
    }
    while(sum_c.size() < b.size()) {
        sum_c += '0';
    }
    // cerr << cur << " " << pw << " " << b << " " << sum_c << '\n';
    if((pw < b.size() && pw < sum_c.size() && sum_c[pw] == b[pw]) || sum_c == b) {
        cur[pw] = '1';
        solve(cur, pw + 1, sum);
    }
    for(int i = 0; i < n; i++) {
        subtract(a[i], pw);
    }
}

void solve2(int cur, int pw, int cur_sum) {
    if(pw > b.size()) {
        if(cur_sum == b_int) {
            ans_int = cur;
        }
        return;
    }
    // cerr << cur << " " << cur_sum << " " << bin(cur) << " " << bin(cur_sum) << '\n';
    if(((cur_sum >> pw) & 1) == ((b_int >> pw) & 1)) {
        solve2(cur, pw + 1, cur_sum);
    }
    if(ans_int != -1) {
        return;
    }
    int sum = 0;
    for(int i = 0; i < n; i++) {
        a_int[i] += (1ll << pw);
        sum ^= a_int[i];
    }
    if(((sum >> pw) & 1) == ((b_int >> pw) & 1)) {
        cur += (1ll << pw);
        solve2(cur, pw + 1, sum);
    }
    for(int i = 0; i < n; i++) {
        a_int[i] -= (1ll << pw);
    }
}

signed main() {
    seriy();
    int KEK = 1;
    while(KEK--) {
        cin >> n;
        a.resize(n);
        a_int.resize(n);
        int cur_sum_int = 0;
        string cur_sum = "0";
        for(int i = 0; i < n; i++) {
            string h;
            cin >> h;
            a[i] = h;
            reverse(all(a[i]));
            a_int[i] = dec(a[i]);
            cur_sum_int ^= a_int[i];
            cur_sum = xor1(cur_sum, a[i]);
        }
        string bb;
        cin >> bb;
        b = bb;
        reverse(all(b));
        b_int = dec(b);
        string s;
        s.resize(b.size() + 1, '0');
        solve(s, 0, cur_sum);
        solve2(0, 0, cur_sum_int);
        while(ans.back() == '0') {
            ans.pop_back();
        }
        reverse(all(ans));
        if(ans == "1-") ans = "-1";
        if(!ans.size()) ans = "0";
        string res = ((ans_int == -1) ? "-1" : bin(ans_int));
        cout << ans;
    }
    return 0;
}