import java.util.*;

public class Main {
    static int[] xArr;
    static int[] yArr;
    static int[] cArr;
    static int[][][] dp;
    static int fee;
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int goalX = sc.nextInt();
		int goalY = sc.nextInt();
		int n = sc.nextInt();
		fee = sc.nextInt();
		xArr = new int[n];
		yArr = new int[n];
		cArr = new int[n];
		for (int i = 0; i < n; i++) {
		    xArr[i] = sc.nextInt();
		    yArr[i] = sc.nextInt();
		    cArr[i] = sc.nextInt();
		}
		dp = new int[n][goalX + 1][goalY + 1];
		System.out.println(dfw(n - 1, goalX, goalY));
	}
	
	static int dfw(int idx, int x, int y) {
	    if (idx < 0) {
	        return (x + y) * fee;
	    }
	    if (dp[idx][x][y] != 0) {
	        return dp[idx][x][y];
	    }
	    dp[idx][x][y] = dfw(idx - 1, x, y);
	    if (xArr[idx] <= x && yArr[idx] <= y)  {
	        dp[idx][x][y] = Math.min(dp[idx][x][y], dfw(idx - 1, x - xArr[idx], y - yArr[idx]) + cArr[idx]);
	    }
	    return dp[idx][x][y];
	}
}