import static java.lang.Math.*;
import static java.util.Arrays.*;
import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	
	long INF = 1L << 61;
	
	long add(long a, long b) {
		return a + b < INF ? (a + b) : INF;
	}
	
	long mul(long a, long b) {
		return (double)a * b < INF ? (a * b) : INF;
	}
	
	// O(nmw)
	void solve() {
		int n = sc.nextInt(), m = sc.nextInt();
		long K = sc.nextLong();
		char[][] words = new char[n][];
		for (int i = 0; i < n; i++) words[i] = sc.next().toCharArray();
		long[] count = new long[m + 1];
		count[0] = 1;
		for (int i = 0; i < m; i++) {
			for (int j = 0; j < n; j++) {
				int i2 = i + words[j].length;
				if (i2 <= m) count[i2] = add(count[i2], count[i]);
			}
		}
		if (count[m] < K) {
			System.out.println("-");
			return;
		}
		char[] res = new char[m];
		long[] num = new long[m + 1];
		num[0] = 1;
		boolean[][] ok = new boolean[n][];
		for (int i = 0; i < n; i++) {
			ok[i] = new boolean[words[i].length];
			ok[i][0] = words[i].length <= m;
		}
		for (int i = 0; i < m; i++) {
			long[] next = new long[26];
			for (int j = 0; j < n; j++) {
				for (int k = 0; k < words[j].length; k++) if (ok[j][k]) {
					int c = words[j][k] - 'a';
					next[c] = add(next[c], mul(num[i - k], count[m - i + k - words[j].length]));
				}
			}
			for (int c = 0; c < 26; c++) {
				if (K <= next[c]) {
					res[i] = (char)('a' + c);
					for (int j = 0; j < n; j++) {
						for (int k = words[j].length - 1; k >= 0; k--) if (ok[j][k]) {
							if (words[j][k] == 'a' + c) {
								if (k + 1 == words[j].length) num[i + 1] = add(num[i + 1], num[i - k]);
								else ok[j][k + 1] = true;
							}
							ok[j][k] = false;
						}
						ok[j][0] = i + 1 + words[j].length <= m;
					}
					break;
				}
				K -= next[c];
			}
		}
		System.out.println(String.valueOf(res));
	}
	
	void run() {
		while (sc.hasNext()) solve();
	}
	
	void debug(Object...os) {
		System.err.println(deepToString(os));
	}
	
	public static void main(String[] args) {
		new Main().run();
	}
}