#include <bits/stdc++.h>

using namespace std;

int cnt[26] = {};

int main() {
    freopen("kstring.in","r",stdin);
    freopen("kstring.out","w",stdout);

    string s; cin >> s;
    int k; cin >> k;

    if (k == 1) {
        cout << s << endl;
        return 0;
    }

    for (char symbol : s) cnt[(symbol - 'a')]++;

    for (int i = 0; i < 26; i++) {
        if (cnt[i] % k != 0) {
            cout << -1 << endl;
            return 0;
        }
    }

    for (int i = 0; i < 26; i++) cnt[i] /= k;

    for (int i = 0; i < k; i++) {
        for (int j = 0; j < 26; j++) {
            for (int k = 0; k < cnt[j]; k++) {
                cout << char('a' + j);
            }
        }
    }

    cout << endl;

    return 0;
}