#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)




int GX, GY, N, F;
int X[60], Y[60], C[60];
//-----------------------------------------------------------------------------------
#define INF INT_MAX/2
int dp[101][101][101];
int main() {
	cin >> GX >> GY >> N >> F;
	rep(i, 0, N) cin >> X[i] >> Y[i] >> C[i];

	rep(i, 0, N) if ((X[i] + Y[i]) * F < C[i]) C[i] = (X[i] + Y[i]) * F;

	rep(i, 0, N + 1) rep(y, 0, GY + 1) rep(x, 0, GX + 1) dp[i][y][x] = INF;
	dp[0][0][0] = 0;
	rep(i, 0, N) rep(y, 0, GY + 1) rep(x, 0, GX + 1) {
		dp[i + 1][y][x] = min(dp[i + 1][y][x], dp[i][y][x]);
		int xx = x + X[i];
		int yy = y + Y[i];
		if (GX < xx) continue;
		if (GY < yy) continue;
		dp[i + 1][yy][xx] = min(dp[i + 1][yy][xx], dp[i][y][x] + C[i]);
	}

	int ans = INF;
	rep(y, 0, GY + 1) rep(x, 0, GX + 1) {
		int c = ((GY - y) + (GX - x)) * F + dp[N][y][x];
		ans = min(ans, c);
	}

	cout << ans << endl;
}