#include <bits/stdc++.h>
using namespace std;
long long int n, l, k, i, j, a, b, x[30];
string s, ans[1010];
char ch(long long int u) {
  long long int u0 = u + 96;
  return (char)u0;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> l >> k >> s;
  for (i = 0; i < 27; i++) x[i] = 0;
  for (i = 0; i < n * l; i++) x[(s[i] - 'a') + 1]++;
  a = 1;
  for (j = 1; j < l + 1; j++) {
    b = 1;
    for (i = a; i < k + 1; i++) {
      while (x[b] == 0) b++;
      ans[i] = ans[i] + ch(b);
      x[b]--;
    }
    while (ans[a][j - 1] != ans[k][j - 1]) a++;
  }
  b = 1;
  for (j = 1; j < n + 1; j++) {
    a = ans[j].size();
    for (i = a + 1; i < l + 1; i++) {
      while (x[b] == 0) b++;
      ans[j] = ans[j] + ch(b);
      x[b]--;
    }
  }
  for (i = 1; i < n + 1; i++) cout << ans[i] << "\n";
}
