#include <iostream>
#include <vector>
#include <algorithm>

struct crystal{
	int x;
	int y;
	int c;
	int safe;
};


using namespace std;

int Gx,Gy;
int N,F;

int main(){
	cin >> Gx >> Gy >> N >> F;
	vector<crystal> vec;
	int mx,my,mc,safe;
	for(int i = 0; 	i < N; i++){
		cin >> mx >> my >> mc;
		if((mx+my)*F > mc){
			safe = (mx+my)*F-mc;
			vec.push_back({mx,my,mc,safe});
		}//歩くよりもコストが少ない
	}
	sort(vec.begin(),vec.end(), [](crystal& a,crystal& b) {
		return (a.safe < b.safe);
	});
/*
	for(auto e: vec){
		 << e.x << "," << e.y << "," << e.c << "," << e.safe<<endl;
	}
*/
int x = 0, y = 0,cost = 0;
	for(int i = 0; i < vec.size(); i++){
		if(vec[i].x + x <= Gx && vec[i].y + y <= Gy){
			x += vec[i].x;
			y += vec[i].y;
			cost += vec[i].c;
		}
	}	
	cost += (Gx - x);
	cost += (Gy - y);
	cout << cost << endl;
	return 0;
}