Gx, Gy, N, F = map(int, input().split())
XYC = [list(map(int, input().split())) for _ in range(N)]
INF = 10 ** 10
dp = [[INF] * (Gy + 1) for _ in range(Gx + 1)]
dp[0][0] = 0
ans = (Gx + Gy) * F
for x, y, c in XYC:
    for i in reversed(range(Gx - x + 1)):
        for j in reversed(range(Gy - y + 1)):
            if dp[i][j] != INF:
                if dp[i + x][j + y] > dp[i][j] + c:
                    dp[i + x][j + y] = dp[i][j] + c
                    ans = min(ans, dp[i + x][j + y] + (Gx - i - x + Gy - j - y) * F)
print(ans)