import java.io.*; import java.util.*; public class Main { static int[][][] dp; static int[] xs; static int[] ys; static int[] cs; static int f; public static void main(String[] args) throws Exception { Scanner sc = new Scanner(); int gx = sc.nextInt(); int gy = sc.nextInt(); int n = sc.nextInt(); f = sc.nextInt(); xs = new int[n]; ys = new int[n]; cs = new int[n]; for (int i = 0; i < n; i++) { xs[i] = sc.nextInt(); ys[i] = sc.nextInt(); cs[i] = sc.nextInt(); } dp = new int[n][gx + 1][gy + 1]; System.out.println(dfw(n - 1, gx, gy)); } static int dfw(int idx, int x, int y) { if (x < 0 || y < 0) { return Integer.MAX_VALUE / 2; } if (idx < 0) { return (x + y) * f; } if (dp[idx][x][y] == 0) { dp[idx][x][y] = Math.min(dfw(idx - 1, x, y), dfw(idx - 1, x - xs[idx], y - ys[idx]) + cs[idx]); } return dp[idx][x][y]; } } class Scanner { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer st = new StringTokenizer(""); StringBuilder sb = new StringBuilder(); public Scanner() throws Exception { } public int nextInt() throws Exception { return Integer.parseInt(next()); } public long nextLong() throws Exception { return Long.parseLong(next()); } public double nextDouble() throws Exception { return Double.parseDouble(next()); } public String next() throws Exception { while (!st.hasMoreTokens()) { st = new StringTokenizer(br.readLine()); } return st.nextToken(); } }