/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Main
{
    public static void main (String[] args) throws java.lang.Exception
    {
        // your code goes here
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] lines = br.readLine().split(" ");
        int gx = Integer.parseInt(lines[0]);
        int gy = Integer.parseInt(lines[1]);
        int n  = Integer.parseInt(lines[2]);
        int f  = Integer.parseInt(lines[3]);
        
        Place start = new Place(0,0);
        Place goal = new Place(gx,gy);
        ArrayList<Crystal> crystals = new ArrayList<Crystal>();
        for(int i=0;i<n;i++){
            crystals.add(new Crystal(i,br.readLine()));
        }
        
        PriorityQueue<Place> queue = new PriorityQueue<Place>(1, new Comparator<Place>(){
            public int compare(Place p1,Place p2){
                return p1.c-p2.c;
            }
        });
        queue.add(start);
        while(!queue.isEmpty()){
            Place now = queue.poll();
            if(now.x == goal.x && now.y == goal.y){
                goal = now;
                break;
            }
            for(Crystal c:crystals){
                if(now.canUseCrystal(c)){
                    Place newPlace = now.clone();
                    newPlace.useCrystal(c);
                    if(newPlace.x <= goal.x && newPlace.y <= goal.y){
                        queue.add(newPlace);
                    }
                }
            }
            Place newPlace = now.clone();
            newPlace.move(goal,f);
            queue.add(newPlace);
        }
        System.out.println(goal.c);
    }
    private static class Place{
        int x,y;
        int c;
        ArrayList<Integer> useCrystal = new ArrayList<Integer>();
        
        public Place(int x,int y){
            this.x = x;
            this.y = y;
            this.c = 0;
        }
        public Place clone(){
            Place p = new Place(this.x,this.y);
            p.c = this.c;
            for(int n:this.useCrystal){
                p.useCrystal.add(n);
            }
            return p;
        }
        public boolean canUseCrystal(Crystal c){
            return useCrystal.indexOf(c.no)==-1;
        }
        public void useCrystal(Crystal c){
            this.x += c.x;
            this.y += c.y;
            this.c += c.c;
            useCrystal.add(c.no);
        }
        public void move(Place g,int f){
            int cost = f*(g.x-this.x);
            cost += f*(g.y-this.y);
            this.x = g.x;
            this.y = g.y;
            this.c += cost;
        }
    }
    private static class Crystal{
        public int no;
        public int x,y,c;
        public Crystal(int no,String line){
            this.no = no;
            String[] lines = line.split(" ");
            this.x = Integer.parseInt(lines[0]);
            this.y = Integer.parseInt(lines[1]);
            this.c = Integer.parseInt(lines[2]);
        }
    }
}