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

#define ll long long
#define fast ios::sync_with_stdio(0); cin.tie(0); cout.tie(0) 
#define v(t) vector<t>
#define pb(e) .push_back(e)
#define mp(a,b) .make_pair(a,b)
#define fe(e,a) for(auto e : a)
#define rang(a) a.begin(), a.end()

int main()
{   
    fast;
    #ifdef ONLINE_JUDGE
    freopen("kstring.in", "r", stdin);
    freopen("kstring.out", "w", stdout);
    #endif

    string s; cin >> s;
    int k,n = s.length(); cin >> k;
    if(n%k!=0) {cout << -1 << "\n"; return 0;}
    // sort(rang(s));
    map<char, int> un;
    for(auto c : s)
    {
        un.count(c)<1 ? un[c]=1 : un[c]++;
    }
    int c= 0;
    string r="";
    for(auto p : un)
    {
        if(c==n/k) break;
        if(p.second % k != 0) {cout << -1 << "\n"; return 0;}
        r+=p.first;
        c++;
    }

    string f;
    int tys = (n/k)/r.length();
    while (tys--)
    {
        f+=r;
    }
    
    cout << f << "\n";
}