import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		solver();
	}

	static void solver() {
		int INF = Integer.MAX_VALUE / 4;
		Scanner sc = new Scanner(System.in);
		int gx = sc.nextInt();
		int gy = sc.nextInt();
		int n = sc.nextInt();
		int f = sc.nextInt();
		int[] x = new int[n];
		int[] y = new int[n];
		int[] c = new int[n];
		for (int i = 0; i < n; i++) {
			x[i] = sc.nextInt();
			y[i] = sc.nextInt();
			c[i] = sc.nextInt();
		}
		int[][] map = new int[101][101];
		for (int i = 0; i <= 100; i++) {
			for (int j = 0; j <= 100; j++) {
				map[i][j] = INF;
			}
		}
		map[0][0] = 0;
		long ans = f * (gx + gy);
		for (int i = 0; i < n; i++) {
			if (c[i] < (x[i] + y[i]) * f) {
				for (int sum = gx + gy; sum >= 0; sum--) {
					for (int xx = gx; xx >= 0; xx--) {
						int yy = sum - gx;
						if (yy < 0 || yy > gy)
							continue;
						if (map[xx][yy] != INF) {
							if (xx + x[i] <= gx && yy + y[i] <= gy) {
								map[xx + x[i]][yy + y[i]] = Math.min(map[xx][yy] + c[i], map[xx + x[i]][yy + y[i]]);
								ans = Math.min(ans, f * (gx + gy - xx - yy - x[i] - y[i]) + map[xx + x[i]][yy + y[i]]);
							}
						}
					}
				}
			} else {
				continue;
			}
		}
		System.out.println(ans);
	}
}