using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    const int inf = 1145141919;

    static int gx, gy, n, f;
    static int[] cx, cy, c;
    
    static T Min<T>(T x, T y) where T : IComparable
    {
        return x.CompareTo(y) < 0 ? x : y;
    }

    static int Search(int x, int y, int sum, List<int> cs)
    {
        if (x == gx && y == gy) return sum;
        if (x > gx || y > gy) return inf;
        int min = inf;
        min = Min(min, Search(x + 1, y, sum + f, cs));
        min = Min(min, Search(x, y + 1, sum + f, cs));
        for (var i = 0; i < n; i++)
        {
            if (cs.Contains(i))
            {
                var cs2 = new List<int>(cs);
                cs2.Remove(i);
                min = Min(min, Search(x + cx[i], y + cy[i], sum + c[i], cs2));
            }
        }
        return min;
    }

    static void Main()
    {
        {
            var tmp = Console.ReadLine().Split().Select(int.Parse).ToArray();
            gx = tmp[0]; gy = tmp[1]; n = tmp[2]; f = tmp[3];
            cx = new int[n]; cy = new int[n]; c = new int[n];
        }
        for (var i = 0; i < n; i++)
        {
            var tmp = Console.ReadLine().Split().Select(int.Parse).ToArray();
            cx[i] = tmp[0]; cy[i] = tmp[1]; c[i] = tmp[2];
        }
        var cs = new List<int>(n);
        for (var i = 0; i < n; i++) cs.Add(i);
        var ans = Search(0, 0, 0, cs);
        Console.WriteLine(ans);
    }
}