using System;
using System.Collections.Generic;
using System.Linq;
using Debug = System.Diagnostics.Debug;
//using System.Numerics;
//using static System.Math;
//using Number = System.Int64;

namespace Program {
    public class Solver {
        //const long MOD = (long)1e9 + 7;
        public void Solve() {
            var n = ri;
            var m = ri;
            var k = rl - 1;
            var s = Enumerate(n, x => rs);
            var pat = new long[m + 1];
            pat[0] = 1;
            for (int i = 0; i < m; i++)
                foreach (var x in s)
                    if (i + x.Length <= m) pat[i + x.Length] = Math.Min(pat[i + x.Length] + pat[i], INF);

            var ans = Enumerate(m, x => '?');
            var dp = new long[m + 1];
            dp[0] = 1;
            var pass = Enumerate(m, x => new bool[n]);

            Func<int, long[][]> f = pos => {
                var ret = Enumerate(26, x => new long[2]);
                for (int d = 0; d < 202; d++) {
                    if (pos - d < 0) break;
                    var i = pos - d;
                    for (int p = 0; p < n; p++) {
                        if (pass[i][p]) continue;
                        var len = s[p].Length;
                        if (i + len <= pos || i + len > m) continue;
                        var c = s[p][d] - 'a';
                        if (ans[pos] != '?' && ans[pos] != s[p][d]) pass[i][p] = true;
                        var add = dp[i] * pat[m - (i + len)];
                        if (1.0 * dp[i] * pat[m - (i + len)] >= INF) add = INF;
                        ret[c][0] = Math.Min(ret[c][0] + add, INF);
                        if (i + len == pos + 1) ret[c][1] = Math.Min(ret[c][1] + dp[i], INF);
                    }
                }
                return ret;
            };
            for (int i = 0; i < m; i++) {
                var ok = false;
                var res = f(i);
                for (char c = 'a'; c <= 'z'; c++) {
                    ans[i] = c;
                    var cc = c - 'a';
                    if (res[cc][0] <= k) k -= res[cc][0];
                    else {
                        ok = true;
                        dp[i + 1] = res[cc][1]; break;
                    }
                }
                f(i);
                if (!ok) {
                    Debug.WriteLine(ans.AsString());
                    Console.WriteLine("-"); return;
                }
            }
            Debug.WriteLine(dp.AsJoinedString());
            Console.WriteLine(ans.AsString());
        }

        const long INF = 1L << 60;
        //int[] dx = { 1, 0, -1, 0 };
        //int[] dy = { 0, 1, 0, -1 };
        //*
        int ri { get { return sc.Integer(); } }
        long rl { get { return sc.Long(); } }
        double rd { get { return sc.Double(); } }
        string rs { get { return sc.Scan(); } }
        //*/

        public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<int, T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; }
        static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    }
}

#region main
static class Ex {
    static public string AsString(this IEnumerable<char> ie) { return new string(ie.ToArray()); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") {
        return string.Join(st, ie.Select(x => x.ToString()).ToArray());
        //return string.Join(st, ie);
    }
    static public void Main() {
        Console.SetOut(new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        var solver = new Program.Solver();
        solver.Solve();
        Console.Out.Flush();
    }
}
#endregion
#region Ex
namespace Program.IO {
    using System.Globalization;
    using System.IO;
    using System.Text;
    public class Printer: StreamWriter {
        public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
        public Printer(Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
    }
    public class StreamScanner {
        public StreamScanner(Stream stream) { str = stream; }
        public readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream { get { return isEof; } }
        private byte read() {
            if (isEof) return 0;
            if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } }
            return buf[ptr++];
        }
        public char Char() { byte b = 0; do b = read(); while ((b < 33 || 126 < b) && !isEof); return (char)b; }

        public string Scan() {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        public string ScanLine() {
            var sb = new StringBuilder();
            for (var b = Char(); b != '\n' && b != 0; b = (char)read())
                if (b != '\r') sb.Append(b);
            return sb.ToString();
        }
        public long Long() { return isEof ? long.MinValue : long.Parse(Scan()); }
        public int Integer() { return isEof ? int.MinValue : int.Parse(Scan()); }
        public double Double() { return isEof ? double.NaN : double.Parse(Scan(), CultureInfo.InvariantCulture); }
    }
}
#endregion


Measured memory_bytes: 10344