#include <bits/stdc++.h>
using namespace std;
int N, L, K;
string s;
int cnt[26];
string res[1000];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> N >> L >> K;
  cin >> s;
  for (int i = 0; i < N * L; i++) cnt[s[i] - 'a']++;
  int l = 0;
  int t = 0;
  while (l < K - 1 and t < 26) {
    int st = cnt[t];
    for (int j = 0, _t = cnt[t]; j < _t; j++) {
      if (res[l + j % (K - l)].size() == L) {
        l = K + 1;
        break;
      }
      res[l + j % (K - l)] += (char)(t + 'a');
      cnt[t]--;
    }
    l += st % (K - l);
    t++;
  }
  int lst = 25;
  for (int i = 0; i < K - 1; i++) {
    while (res[i].size() < L) {
      while (cnt[lst] == 0) lst--;
      res[i] += (char)(lst + 'a');
      cnt[lst]--;
    }
  }
  int fst = 0;
  for (int i = K - 1; i < N; i++) {
    while (res[i].size() < L) {
      while (cnt[fst] == 0) fst++;
      res[i] += (char)(fst + 'a');
      cnt[fst]--;
    }
  }
  sort(res, res + N);
  for (int i = 0; i < N; i++) {
    cout << res[i] << '\n';
  }
}
