#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
using namespace std;

struct POS {
	int x, y;

	bool operator<(const POS &right)const {
		return x + y > right.x + right.y;
	}
};

int main()
{
	int Gx, Gy, N, F;cin >> Gx >> Gy >> N >> F;
	
	vector<pair<POS,int>>xyc(N);
	for (int i = 0;i < N;i++) {
		cin >> xyc[i].first.x >> xyc[i].first.y >> xyc[i].second;
	}
	sort(xyc.begin(), xyc.end());

	map<POS, int>M;
	POS p = { 0,0 };
	M[p] = 0;
	for (int i = 0;i < N;i++) {
		for (auto itr = M.begin();itr != M.end();itr++) {
			POS pos = itr->first;
			pos.x += xyc[i].first.x;pos.y += xyc[i].first.y;
			if (pos.x > Gx || pos.y > Gy)continue;
			if (M.find(pos) == M.end()) {
				M[pos] = itr->second + xyc[i].second;
			}
			else M[pos] = min(M[pos], itr->second + xyc[i].second);
		}
	}

	int ans = 1e8;
	for (auto itr = M.begin();itr != M.end();itr++) {
		ans = min(ans, itr->second + F*abs(itr->first.x - Gx) + F*abs(itr->first.y - Gy));
	}

	cout << ans << endl;

    return 0;
}