#include <bits/stdc++.h>

using namespace std;

#define rep(i, x) for (int i = 0; i < x; ++i)
#define rrep(i, x) for (int i = x-1; i >= 0; --i)

const int inf = 1e9;

int X[55], Y[55], C[55];

int dp[105][105];

int main()
{
    int gx, gy; cin >> gx >> gy;
    int N, F; cin >> N >> F;
    rep(i, N) {
        cin >> X[i] >> Y[i] >> C[i];
    }

    rep(i, 105) rep(j, 105) dp[i][j] = inf;
    dp[0][0] = 0;

    rep(i, N) {
        rrep(y, 103) rrep(x, 103) {
            if (y-Y[i] < 0 || x-X[i] < 0) continue;
            if (dp[y-Y[i]][x-X[i]] == inf) continue;
            dp[y][x] = min(dp[y][x], dp[y-Y[i]][x-X[i]] + C[i]);
        }
    }

    int ans = inf;

    rep(y, 103) rep(x, 103) {
        if (dp[y][x] == inf) continue;
        if (gy - y < 0 || gx - x < 0) continue;
        ans = min(ans, dp[y][x] + (gy - y + gx - x) * F);
    }

    cout << ans << endl;
}