#include "bits/stdc++.h"

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

using namespace std;

using LL = long long int;
using LD = long double;

using pii = pair<int, int>;
using pll = pair<LL, LL>;
using pdd = pair<double, double>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<LL>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vvd = vector<vd>;
using vs = vector<string>;
using vb = vector<bool>;
using vvb = vector<vb>;

const int INF = (1 << 30) - 1;
const LL INF64 = ((LL)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;

const int dy[] = { 0, 1, 0, -1 };
const int dx[] = { 1, 0, -1, 0 };

int gcd(int x, int y) { return y ? gcd(y, x % y) : x; }
LL gcd(LL x, LL y) { return y ? gcd(y, x % y) : x; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	int gx, gy, n, f;
	cin >> gx >> gy >> n >> f;

	vvi dp(gy + 1, vi(gx + 1));
	for (int i = 0; i <= gy; i++) {
		for (int j = 0; j <= gx; j++) {
			dp[i][j] = f * i + f * j ;
		}
	}

	for (int i = 0; i < n; i++) {
		int x, y, c;
		cin >> x >> y >> c;
		for (int j = gy; j - y >= 0; j--) {
			for (int k = gx; k - x >= 0; k--) {
				dp[j][k] = min(dp[j][k], dp[j - y][k - x] + c);
			}
		}
	}

	cout << dp[gy][gx] << endl;
	return 0;
}