#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long a, b, c, d, e, f, i, j, k, l, m, n, o, x, y;
  cin >> n >> l >> k;
  string ss;
  cin >> ss;
  deque<char> dq;
  for (char c : ss) dq.push_back(c);
  sort(dq.begin(), dq.end());
  string s[n + 5];
  long long cnt = k;
  for (j = 0; j < l; j++) {
    long long cc = 0;
    for (i = 0; i < cnt; i++) {
      if (dq[cnt - 1] != dq[i]) cc++;
      s[k - cnt + i].push_back(dq[i]);
    }
    for (i = 0; i < cnt; i++) dq.pop_front();
    cnt -= cc;
  }
  for (i = 0; i < n; i++) {
    if (s[i].size() < l) {
      while (true) {
        s[i].push_back(dq.front());
        dq.pop_front();
        if (s[i].size() == l) break;
      }
    }
  }
  for (i = 0; i < n; i++) {
    for (char c : s[i]) cout << c;
    cout << "\n";
  }
}
