using static System.Math;
using System.Collections.Generic;
using System;

public class PriorityQueue<T> where T : IComparable
{
    private IComparer<T> _comparer = null;
    private int _type = 0;
    private T[] _heap;
    private int _sz = 0;
    private int _count = 0;
    /// <summary>
    /// Priority Queue with custom comparer
    /// </summary>
    public PriorityQueue(int maxSize, IComparer<T> comparer)
    {
        _heap = new T[maxSize];
        _comparer = comparer;
    }

    /// <summary>
    /// Priority queue
    /// </summary>
    /// <param name="maxSize">max size</param>
    /// <param name="type">0: asc, 1:desc</param>
    public PriorityQueue(int maxSize, int type = 0)
    {
        _heap = new T[maxSize];
        _type = type;
    }
    private int Compare(T x, T y)
    {
        if (_comparer != null) return _comparer.Compare(x, y);
        return _type == 0 ? x.CompareTo(y) : y.CompareTo(x);
    }
    public void Push(T x)
    {
        _count++;
        //node number
        var i = _sz++;
        while (i > 0)
        {
            //parent node number
            var p = (i - 1) / 2;

            if (Compare(_heap[p], x) <= 0) break;

            _heap[i] = _heap[p];
            i = p;
        }
        _heap[i] = x;
    }
    public T Pop()
    {
        _count--;
        T ret = _heap[0];
        T x = _heap[--_sz];

        int i = 0;
        while (i * 2 + 1 < _sz)
        {
            //children
            int a = i * 2 + 1;
            int b = i * 2 + 2;

            if (b < _sz && Compare(_heap[b], _heap[a]) < 0) a = b;

            if (Compare(_heap[a], x) >= 0) break;

            _heap[i] = _heap[a];
            i = a;
        }
        _heap[i] = x;
        return ret;
    }
    public int Count()
    {
        return _count;
    }
    public T Peek()
    {
        return _heap[0];
    }
    public bool Contains(T x)
    {
        for (int i = 0; i < _sz; i++) if (x.Equals(_heap[i])) return true;
        return false;
    }
    public void Clear()
    {
        while (this.Count() > 0) this.Pop();
    }
    public IEnumerator<T> GetEnumerator()
    {
        var ret = new List<T>();
        while (this.Count() > 0)
        {
            ret.Add(this.Pop());
        }
        foreach (var r in ret)
        {
            this.Push(r);
            yield return r;
        }
    }
    public T[] ToArray()
    {
        T[] array = new T[_sz];
        int i = 0;
        foreach (var r in this)
        {
            array[i++] = r;
        }
        return array;
    }
}

public class Edge
{
    public int to1 { get; set; }
    public int to2 { get; set; }
    public long d { get; set; }
}
public class Node : IComparable
{
    public int id1 { get; set; }
    public int id2 { get; set; }
    public long d { get; set; }
    public int CompareTo(object obj)
    {
        var x = (Node)obj;
        if (this.d > x.d) return 1;
        else if (this.d == x.d) return 0;
        else return -1;
    }
}

public class hello
{
    public static void Main()
    {
        while (true)
        {
            string[] line = Console.ReadLine().Trim().Split(' ');
            var m = int.Parse(line[0]);
            var n = int.Parse(line[1]);
            var k = int.Parse(line[2]);
            var d = int.Parse(line[3]);
            if (m == 0 && n == 0 && k == 0 && d == 0) break;
            line = Console.ReadLine().Trim().Split(' ');
            var c = Array.ConvertAll(line, int.Parse);
            var dic = new Dictionary<string, int>();
            var dicp = 0;
            var home = 0; var office = 0;
            var aa = new List<Edge>[108, 1 << m];
            var mind = new long[108, 1 << m];
            for (int i = 0; i < 108; i++)
                for (int j = 0; j < 1 << m; j++)
                {
                    aa[i, j] = new List<Edge>();
                    mind[i, j] = 9999999999999;
                }
            for (int i = 0; i < d; i++)
            {
                line = Console.ReadLine().Trim().Split(' ');
                var s = line[0];
                var t = line[1];
                var e = int.Parse(line[2]);
                if (!dic.ContainsKey(s))
                {
                    dic[s] = dicp++;
                    if (s == "H") home = dic[s];
                    if (s == "D") office = dic[s];
                }
                if (!dic.ContainsKey(t))
                {
                    dic[t] = dicp++;
                    if (t == "H") home = dic[t];
                    if (t == "D") office = dic[t];
                }
                setEdge(aa, dic, c, m, k, d, s, t, e);
                setEdge(aa, dic, c, m, k, d, t, s, e);
            }
            goDijk(aa, home, 0, mind);
            print(mind, m, office);
        }
    }
    static void print(long[,] mind, int m, int office)
    {
        var ans = long.MaxValue;
        for (int i = 0; i < 1 << m; i++)
            ans = Min(ans, mind[office, i]);
        Console.WriteLine(ans);
    }
    static void setEdge(List<Edge>[,] aa, Dictionary<string, int> dic, int[] c, int m, int k, int d, string s, string t, int e)
    {
        var start1 = dic[s]; var to1 = dic[t];
        if (s[0] == 'C' && t[0] == 'C')
        {
            for (int i = 0; i < 1 << m; i++)
            {
                var w = checkCake(i, m, s[1] - '0' - 1);
                if (w != -1)
                {
                    var w2 = checkCake(w, m, t[1] - '0' - 1);
                    if (w2 != -1)
                        aa[start1, w].Add(new Edge { to1 = to1, to2 = w2, d = e * k - c[t[1] - '0' - 1] });
                }
            }
        }
        else if (s[0] == 'C' && t[0] != 'C')
        {
            for (int i = 0; i < 1 << m; i++)
            {
                var w = checkCake(i, m, s[1] - '0' - 1);
                if (w != -1)
                    aa[start1, w].Add(new Edge { to1 = to1, to2 = w, d = e * k });
            }
        }
        else if (s[0] != 'C' && t[0] == 'C')
        {
            for (int i = 0; i < 1 << m; i++)
            {
                var w2 = checkCake(i, m, t[1] - '0' - 1);
                if (w2 != -1)
                    aa[start1, i].Add(new Edge { to1 = to1, to2 = w2, d = e * k - c[t[1] - '0' - 1] });
            }
        }
        else
        {
            for (int i = 0; i < 1 << m; i++)
                aa[start1, i].Add(new Edge { to1 = to1, to2 = i, d = e * k });
        }
    }
    static int checkCake(int t, int m, int a)
    {
        if (((t >> m - a - 1) & 1) == 1) return -1;
        else return t | (1 << m - a - 1);
    }
    public static void goDijk(List<Edge>[,] aa, int r1, int r2, long[,] mind)
    {
        var pq = new PriorityQueue<Node>(100000, 0);
        pq.Push(new Node { id1 = r1, id2 = r2, d = 0 });
        while (pq.Count() > 0)
        {
            var targ = pq.Pop();
            var nowd = targ.d;
            var nowid1 = targ.id1;
            var nowid2 = targ.id2;
            if (mind[nowid1, nowid2] < nowd) continue;
            mind[nowid1, nowid2] = nowd;
            foreach (var x in aa[nowid1, nowid2])
                if (nowd + x.d < mind[x.to1, x.to2])
                {
                    mind[x.to1, x.to2] = nowd + x.d;
                    pq.Push(new Node { id1 = x.to1, id2 = x.to2, d = nowd + x.d });
                }

        }
    }
}



Measured memory_bytes: 41648