#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, l, k, i, j, x, c;
  string s;
  cin >> n >> l >> k >> s;
  k--;
  vector<string> ans(n, "");
  sort(s.begin(), s.end());
  queue<int> q;
  for (i = 0; i <= k; i++) q.push(i);
  c = 0;
  while ((ans[k].length() < l) && (!q.empty())) {
    x = q.front();
    q.pop();
    if (ans[x] == ans[k]) {
      ans[x] = ans[x] + s[c++];
      q.push(x);
    }
  }
  for (i = 0; i < n; i++) {
    while (ans[i].length() < l) {
      ans[i] = ans[i] + s[c++];
    }
  }
  for (auto p : ans) cout << p << "\n";
  return 0;
}
