Gx, Gy, N, F = map(int, input().split())
crystals = [tuple(map(int, input().split())) for _ in range(N)]

INF = float('inf')
dp = [[INF] * (Gy + 1) for _ in range(Gx + 1)]
dp[0][0] = 0

for dx, dy, c in crystals:
    for x in range(Gx, -1, -1):
        for y in range(Gy, -1, -1):
            if dp[x][y] == INF:
                continue
            new_x = x + dx
            new_y = y + dy
            if new_x > Gx or new_y > Gy:
                continue
            new_cost = dp[x][y] + (c - F * (dx + dy))
            if new_cost < dp[new_x][new_y]:
                dp[new_x][new_y] = new_cost

min_val = min(dp[x][y] for x in range(Gx + 1) for y in range(Gy + 1))
print(min_val + F * (Gx + Gy))