#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>


/*
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*/


int main() {
	int gx, gy, crystals, fee;

	std::cin >> gx >> gy >> crystals >> fee;

	std::vector<std::pair<std::pair<int, int>, int> > v(crystals);

	for (int i = 0; i < crystals; i++)
	{
		int x, y, f;
		std::cin >> x >> y >> f;

		v[i] = { {x, y}, f };
	};

	long long dp[100][100][100];

	for (int i = 0; i < 100; i++)
	{
		for (int j = 0; j < 100; j++)
		{
			for (int k = 0; k < 100; k++)
			{
				dp[i][j][k] = 10000000000;
			}
		}
	}

	for (int i = 0; i < 100; i++)
	{
		dp[0][0][i] = 0;
	}

	
	for (int i = 0; i <= gy; i++)
	{
		for (int j = 0; j <= gx; j++)
		{

			dp[i + 1][j][0] = std::min(dp[i + 1][j][0], dp[i][j][0] + fee);
			dp[i][j + 1][0] = std::min(dp[i][j + 1][0], dp[i][j][0] + fee);

			for (int k = 0; k < crystals; k++) {
				dp[i][j][k + 1] = std::min(dp[i][j][k + 1], dp[i][j][k]);
				if (v[k].first.first + j <= gx && v[k].first.second + i <= gy) {
					dp[i + v[k].first.second][j + v[k].first.first][k + 1] = std::min(dp[i + v[k].first.second][j + v[k].first.first][k + 1], dp[i][j][k] + v[k].second);
				}
			}
		}
	}

	long long ans = dp[gy][gx][0];
	for (int i = 0; i < crystals; i++)
	{
		ans = std::min(ans, dp[gy][gx][i + 1]);
	}

	std::cout << ans << std::endl;

	return 0;
}