#include <bits/stdc++.h>
using namespace std;
const int N = 1e7;
const long long mod = 998244353;
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(NULL);
  int n, l, k;
  cin >> n >> l >> k;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  s = "?" + s;
  vector<string> ans(n + 1);
  int last;
  vector<int> freq(26, 0);
  for (int i = 1, j = 1; i <= n * l; i++, j++) {
    if (j < k) {
      ans[j].push_back(s[i]);
      freq[s[i] - 'a']++;
    } else {
      ans[k].push_back(s[i]);
      if (ans[k].size() == l) {
        last = i + 1;
        break;
      }
      int cnt = freq[s[i] - 'a'];
      j = k - cnt - 1;
      for (int x = 0; x < 26; x++) freq[x] = 0;
    }
  }
  for (int i = last, j = 1; i <= n * l; i++) {
    while ((j <= n) && ((ans[j].length() == l) || (j == k))) j++;
    ans[j].push_back(s[i]);
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < l; j++) cout << ans[i][j];
    cout << "\n";
  }
  return 0;
}
