#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using PII = std::pair<int, int>;
using PLL = std::pair<ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)


int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    int gx, gy, n, f, x, y, c;
    cin >> gx >> gy >> n >> f;
    int cost[gy + 1][gx + 1], new_cost[gy + 1][gx + 1];
    rep(i, gy + 1)
        rep(j, gx + 1)
            cost[i][j] = (i + j) * f;

    

    rep(i, n)
    {
        rep(i, gy + 1)
            rep(j, gx + 1)
                new_cost[i][j] = cost[i][j];
        cin >> x >> y >> c;
        rep(i, gy + 1)
            rep(j, gx + 1) if (0 <= i + y && i + y <= gy && 0 <= j + x && j + x <= gx)
                new_cost[i + y][j + x] = min(new_cost[i + y][j + x], cost[i][j] + c);
        rep(i, gy + 1)
            rep(j, gx + 1)
                cost[i][j] = new_cost[i][j];
    }

    // rep(i, gy + 1)
    // {
    //     rep(j, gx + 1)
    //         cout << cost[i][j] << " ";
    //     cout << endl;
    // }

    cout << cost[gy][gx] << "\n";
    return 0;
}