# coding: utf-8
import sys

def array2d(d1, d2, init = None):
    return [[init for _ in range(d2)] for _ in range(d1)]

def solve(Gx, Gy, N, F, X, Y, C):
    dp_layer = array2d(Gx + 1, Gy + 1)
    dp_prev_layer = None

    for i in range(-1, N):
        for x in range(Gx + 1):
            for y in range(Gy + 1):
                if x == 0 and y == 0:
                    dp_layer[0][0] = 0
                else:
                    cand = []
                    if x > 0:
                        cand.append(dp_layer[x-1][y] + F)
                    if y > 0:
                        cand.append(dp_layer[x][y-1] + F)
                    if i >= 0:
                        cand.append(dp_prev_layer[x][y])
                        if x > 0:
                            cand.append(dp_prev_layer[x-1][y] + F)
                        if y > 0:
                            cand.append(dp_prev_layer[x][y-1] + F)
                        if x >= X[i] and y >= Y[i]:
                            cand.append(dp_prev_layer[x - X[i]][y - Y[i]] + C[i])
                    dp_layer[x][y] = min(cand)
        dp_prev_layer = dp_layer
        dp_layer = array2d(Gx + 1, Gy + 1)

        # # dbg
        # sys.stderr.write("------\n{} ------\n".format(i))
        # for x in range(Gx + 1):
        #     sys.stderr.write(" ".join(["{:2d}".format(cost) for cost in dp_prev_layer[x]]) + "\n")
    return dp_prev_layer[-1][-1]



def main():
    Gx, Gy, N, F = map(int, input().split())
    x = [None] * N
    y = [None] * N
    c = [None] * N
    for i in range(N):
        x[i], y[i], c[i] = map(int, input().split())
    print(solve(Gx, Gy, N, F, x, y, c))

main()