#include<iostream>
#define min(a,b) a<b?a:b
using namespace std;
int dp[105][105];
const int MAX=100007;
int main(){
	int x,y,n,f;
	int cr[55][4];
	int i,j,k;
	cin>>x>>y>>n>>f;
	for(i=0;i<n;i++){
		for(j=0;j<3;j++){
			cin>>cr[i][j];
		}
	}
	for(i=0;i<105;i++){
		for(j=0;j<105;j++){
			dp[i][j]=MAX;
		}
	}
	dp[0][0]=0;
	for(i=0;i<=x;i++){
		for(j=0;j<=y;j++){
			if(i!=0)dp[i][j]=min(dp[i][j],dp[i-1][j]+f);
			if(j!=0)dp[i][j]=min(dp[i][j],dp[i][j-1]+f);
			for(k=0;k<n;k++){
				if(i<cr[k][0] || j<cr[k][1] || cr[k][3]==1)continue;
				cr[k][3]=1;
				dp[i][j]=min(dp[i][j],dp[i-cr[k][0]][j-cr[k][1]]+cr[k][2]);
			}
		}
	}
	cout<<dp[x][y]<<endl;
	return 0;
}