#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if (y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if (x < y) x = y; }

int main() {
	int Gx; int Gy; int K;
	while (~scanf("%d%d%d", &Gx, &Gy, &K)) {
		int F;
		scanf("%d", &F);
		vector<int> xs(K), ys(K), cs(K);
		rep(i, K) {
			int x; int y; int n;
			scanf("%d%d%d", &x, &y, &n);
			xs[i] = x, ys[i] = y, cs[i] = n;
		}
		vector<vector<int>> dp(Gx + 1, vector<int>(Gy + 1, INF));
		dp[0][0] = 0;
		rep(i, K) {
			for (int x = Gx - xs[i]; x >= 0; -- x)
				for (int y = Gy - ys[i]; y >= 0; -- y)
					amin(dp[x + xs[i]][y + ys[i]], dp[x][y] + cs[i]);
		}
		int ans = INF;
		rer(x, 0, Gx) rer(y, 0, Gy)
			amin(ans, dp[x][y] + F * ((Gx - x) + (Gy - y)));
		printf("%d\n", ans);
	}
	return 0;
}