#include <bits/stdc++.h>

using namespace std;

int X[50];
int Y[50];
int C[50];
int gx,gy,n,f;
int dp[51][101][101];

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

	cin >> gx >> gy >> n >> f;

	for(int i=0;i<n;i++)
	{
		cin >> X[i] >> Y[i] >> C[i];
	}

	for(int i=0;i<=n;i++)
	{
		for(int j=0;j<=100;j++)
		{
			for(int k=0;k<=100;k++)
			{
				dp[i][j][k] = 1e9;
			}
		}
	}

	dp[0][0][0] = 0;

	for(int i=0;i<=n;i++)
	{
		for(int j=0;j<=100;j++)
		{
			for(int k=0;k<=100;k++)
			{
				if(dp[i][j][k]>=1e9) continue;
				if(j+1<=100)
				{
					dp[i][j+1][k] = min(dp[i][j+1][k],dp[i][j][k] + f);
				}
				if(k+1<=100)
				{
					dp[i][j][k+1] = min(dp[i][j][k+1],dp[i][j][k] + f);
				}
				if(i < n && j+X[i]<=100 && k+Y[i]<=100)
				{
					dp[i+1][j+X[i]][k+Y[i]] = min(dp[i+1][j+X[i]][k+Y[i]],dp[i][j][k] + C[i]);
				}
				dp[i+1][j][k] = min(dp[i+1][j][k],dp[i][j][k]);
			}
		}
	}

	int res = 1e9;

	for(int i=0;i<=n;i++)
	{
		res = min(res,dp[i][gx][gy]);
	}

	cout << res << '\n';
	return 0;
}