#include <bits/stdc++.h>
using namespace std;
using i64 = long long int;
using ii = pair<int, int>;
using ii64 = pair<i64, i64>;
int f[27];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int n, l, k;
  cin >> n >> l >> k;
  string s;
  cin >> s;
  sort((s).begin(), (s).end());
  for (int i = s.size() - 1; i >= 0; i--) f[s[i] - 'a'] = i;
  int off = 0;
  int order = k - 1;
  vector<string> result(n);
  while (result[k - 1].size() < l) {
    char c = s[off + order];
    for (int i = 0; i <= order; i++)
      result[k - 1 - order + i].push_back(s[off + i]);
    int cf = f[c - 'a'];
    int norder = off + order - max(off, cf);
    off += order + 1;
    order = norder;
  }
  for (int i = 0; i < n; i++) {
    while (result[i].size() < l) {
      result[i].push_back(s[off]);
      off++;
    }
  }
  for (int i = 0; i < n; i++) cout << result[i] << '\n';
  return 0;
}
