2
aaab
 2
babac
 2
aaaaaabbbb
 1
aabaab
 2
aabbbbccccccdddddddd
 2
abba
 2
aaaazzzz
 250
cececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececece
 3
aaaaaaaaacccdddddd
 2
aabaab
 1
aaaaa
 7
abacaba
 2
aaaabbbb
 5
aaaaa
 1
aaa
 2
aaazz
 3
aabaaaaabb
 2
aaaa
 2
aa
 3
bbbccc
 15
abaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaaabaabbbcababaaa
 1
a
 2
bbaaaa
 2
aaaabb
 2
aabbbb
 2
aaaaaazz
 3
aaaaaaaaacccbbbbbb
 2
bbbbaa
 2
aaaazz
 2
aazzzz
 2
acaccc

-1
 -1
 aaabbaaabb aaaabb
 abbcccddddabbcccdddd abab
 aazzaazz cececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececececece
 aaacddaaacddaaacdd aabaab
 aaaaa
 -1
 aabbaabb
 aaaaa
 aaa
 -1
 -1
 aaaa
 aa
 bcbcbc
 aaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbcaaaaaaaabbbbbbc a
 aabaab
 aabaab
 abbabb
 aaazaaaz aaabbcaaabbcaaabbc
 abbabb
 aazaaz azzazz
 accacc


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashSet;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Scanner;
import java.util.Set;
import java.util.Stack;
import java.util.StringTokenizer;

public class Main {

    static String hex(String s) {
        return new BigInteger(s, 16).toString(2);
    }

    static void ss(char[] cc) {
        for (int e = 0; e < cc.length; e++) {
            for (int q = e + 1; q < cc.length; q++) {
                if ((cc[e] + "").toLowerCase().compareTo(((cc[q] + "").toLowerCase())) > 0) {
                    char g = cc[e];
                    cc[e] = cc[q];
                    cc[q] = g;
                }
            }
        }
    }

    static void s(int[] cc, int m) {
        int c = 0;
        for (int e = 0; e < cc.length; e++) {
            for (int q = e + 1; q < cc.length; q++) {
                if (cc[e] < m) {
                    c++;
                    int g = cc[e];
                    cc[e] = cc[q];
                    cc[q] = g;
                }
            }
        }
        System.out.println(c);
    }

    static int Obe(long a, long b) {
        BigInteger b1 = new BigInteger("" + a);
        BigInteger b2 = new BigInteger("" + b);
        BigInteger gcd = b1.gcd(b2);
        return gcd.intValue();
    }

    private static ArrayList<BigInteger> fibCache = new ArrayList<BigInteger>();

    static {
        fibCache.add(BigInteger.ZERO);
        fibCache.add(BigInteger.ONE);
    }

    public static BigInteger fib(int n) {
        if (n >= fibCache.size()) {
            fibCache.add(n, fib(n - 1).add(fib(n - 2)));
        }

        return fibCache.get(n);
    }

    public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(System.in);
        int[] a = new int[200];
        int n = in.nextInt();
        String s = in.next();
        for (int i = 0; i < s.length(); i++) {
            a[s.charAt(i)]++;
        }
        for (int i = 0; i < 200; i++) {
            if (a[i] != 0 && a[i] != a[s.charAt(0)]) {
                System.out.println("-1");
                return;
            }
        }
        for (int j = 0; j < n; j++) {
            for (int i = 0; i < 200; i++) {
                if (a[i] != 0 && a[i] == a[s.charAt(0)]) {
                    System.out.print((char)i);
                }

            }
        }

    }
}

class Reader {

    static BufferedReader reader;
    static StringTokenizer tokenizer;

    static void init(InputStream input) {
        reader = new BufferedReader(
                new InputStreamReader(input));
        tokenizer = new StringTokenizer("");
    }

    static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(
                    reader.readLine());
        }
        return tokenizer.nextToken();
    }

    static int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    static double nextDouble() throws IOException {
        return Double.parseDouble(next());

    }
}
