#include <bits/stdc++.h>
using namespace std;

int n, cnt[2050];

char a[1000][2050], b[2050], x[2050];

void f (int i) {
    for (int j = 0; j < n; ++j) {
        a[j][i]++;
        for (int k = i; k < 2040 && a[j][k] == 2; ++k) {
            a[j][k] = 0;
            a[j][k + 1]++;
        }
    }
    x[i] += 1;
    for (int k = i; k < 2040 && x[k] == 2; ++k) {
        x[k] = 0;
        x[k + 1]++;
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    freopen("input.txt", "r", stdin);

    cin >> n;
    if (n == 1) {
        string a, b;
        cin >> a >> b;
        int x = 0, y = 0;
        for (int i = 0; i < a.size(); ++i)
            x = x*2 + a[i] - 48;
        for (int i = 0; i < b.size(); ++i)
            y = y*2 + b[i] - 48;
        y -= x;
        if (y < 0) {
            cout << -1;
            return 0;
        }
        string ans;
        while (y) {
            ans = ans + char(y%2 + 48);
            y /= 2;
        }
        if (ans == "")
            cout << 0;
        else
            cout << ans;
        return 0;
    }
    string A;
    for (int i = 0; i < n; ++i) {
        cin >> A;
        reverse(A.begin(), A.end());
        for (int j = 0; j < A.size(); ++j)
            a[i][j] = A[j] - 48;
    }
    cin >> A;
    reverse(A.begin(), A.end());
    for (int j = 0; j < A.size(); ++j)
        b[j] = A[j] - 48;
    for (int i = 0; i < 2050; ++i) {
        for (int j = 0; j < n; ++j) {
            cnt[i] += a[j][i];
        }
        if (cnt[i]%2 && !b[i])
            if (n%2 == 0) {
                if (!i || b[i - 1] && (n - cnt[i - 1])%2 == 0 || !b[i - 1] && (n - cnt[i - 1])%2) {
                    cout << -1;
                    return 0;
                }
                else {
                    f(i - 1);
                    cnt[i] = 0;
                    for (int j = 0; j < n; ++j) {
                        cnt[i] += a[j][i];
                    }
                    if (cnt[i]%2) {
                        cout << -1;
                        return 0;
                    }
                }
            }
            else {
                f(i);
                cnt[i] = n - cnt[i];
            }
        else
            if (cnt[i]%2 == 0 && b[i])
                if (n%2 == 0) {
                    if (!i || b[i - 1] && (n - cnt[i - 1])%2 == 0 || !b[i - 1] && (n - cnt[i - 1])%2) {
                        cout << -1;
                        return 0;
                    }
                    else {
                        f(i - 1);
                        cnt[i] = 0;
                        for (int j = 0; j < n; ++j) {
                            cnt[i] += a[j][i];
                        }
                        if (cnt[i]%2 == 0) {
                            cout << -1;
                            return 0;
                        }
                    }
                }
                else {
                    f(i);
                    cnt[i] = n - cnt[i];
                }
    }
    int i = 2040;
    for (; i && !x[i]; --i);
    if (i > 1999) {
        cout << -1;
        return 0;
    }
    for (; i + 1; --i)
        cout << int(x[i]);

    return 0;
}