#include <bits/stdc++.h>
using namespace std;
int n, l, k;
string s;
string ans[1001];
int cnt[30];
int main() {
  cin >> n >> l >> k;
  cin >> s;
  for (int i = 0; i < s.size(); i++) {
    cnt[s[i] - 'a']++;
  }
  int pos = 0;
  int posk = 1;
  while (posk != k && ans[k].length() < l) {
    for (int i = posk; i <= k; i++) {
      if (cnt[pos] == 0) {
        while (cnt[pos] == 0) pos++;
        posk = i;
      }
      if (cnt[pos] > 0) {
        ans[i] += pos + 'a';
        cnt[pos]--;
      }
    }
  }
  while (ans[k].length() < l) {
    while (cnt[pos] == 0) pos++;
    if (cnt[pos] > 0) {
      ans[k] += pos + 'a';
      cnt[pos]--;
    }
  }
  for (int i = 1; i <= n; i++) {
    while (ans[i].length() < l) {
      while (cnt[pos] == 0) pos++;
      if (cnt[pos] > 0) {
        ans[i] += pos + 'a';
        cnt[pos]--;
      }
    }
  }
  for (int i = 1; i <= n; i++) {
    cout << ans[i] << endl;
  }
  return 0;
}
