#include <iostream>
#include <vector>

template <class T>
std::vector<T> vec(int len, T elem) { return std::vector<T>(len, elem); }

constexpr int INF = 1 << 30;

void solve() {
    int h, w, n, f;
    std::cin >> h >> w >> n >> f;

    auto cost = vec(h + 1, vec(w + 1, INF));
    cost[0][0] = 0;
    while (n--) {
        int dx, dy, c;
        std::cin >> dx >> dy >> c;

        for (int x = h; x >= dx; --x) {
            for (int y = w; y >= dy; --y) {
                cost[x][y] = std::min(cost[x][y], cost[x - dx][y - dy] + c);
            }
        }
    }

    int ans = INF;
    for (int x = 0; x <= h; ++x) {
        for (int y = 0; y <= w; ++y) {
            ans = std::min(ans, cost[x][y] + (h - x + w - y) * f);
        }
    }

    std::cout << ans << "\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}