import java.util.Scanner;

public class Main {
    static Scanner in = new Scanner(System.in);

    public static void main(String[] args) {
        int Gx = in.nextInt(), Gy = in.nextInt(), N = in.nextInt(), F = in.nextInt();
        int[] x = new int[N], y = new int[N], c = new int[N];
        for (int i = 0; i < N; i++) {
            x[i] = in.nextInt();
            y[i] = in.nextInt();
            c[i] = in.nextInt();
        }
        int[][][] dp = new int[N + 1][Gx + 1][Gy + 1];
        for(int i = 0; i < Gx + 1; i++){
            for(int j = 0; j < Gy + 1; j++){
                dp[0][i][j] = (i + j) * F;
            }
        }
        for(int i = 1; i < N + 1; i++){
            for(int j = 0; j < Gx + 1; j++){
                for(int k = 0; k < Gy + 1; k++){
                    if(j != 0){
                        dp[i][j][k] = Math.min(dp[i - 1][j][j], dp[i - 1][j - 1][k] + F);
                    }
                    if(k != 0){
                        dp[i][j][k] = Math.min(dp[i - 1][j][k], dp[i - 1][j][k - 1] + F);
                    }
                    if(j - x[i - 1] >= 0 && k - y[i - 1] >= 0){
                        dp[i][j][k] = Math.min(dp[i - 1][j][k], dp[i - 1][j - x[i - 1]][k - y[i - 1]] + c[i - 1]);
                    }
                }
            }
        }
        System.out.println(dp[N][Gx][Gy]);
    }
}