#include <bits/stdc++.h>
using namespace std;

#define FOR(i,l,r) for(int i = (int) (l);i < (int) (r);i++)
#define ALL(x) x.begin(),x.end()
template<typename T> bool chmax(T& a,const T& b){ return a < b ? (a = b,true) : false; }
template<typename T> bool chmin(T& a,const T& b){ return b < a ? (a = b,true) : false; }
typedef long long ll;

int gx,gy,N,F;
int dp [51] [101] [101];
const int INF = 1e9;

int main()
{
	scanf("%d%d%d%d",&gx,&gy,&N,&F);
	vector<int> X(N),Y(N),C(N);
	FOR(i,0,N){
		scanf("%d%d%d",&X [i],&Y [i],&C [i]);
	}

	fill(dp [0] [0],dp [N + 1] [0],INF);
	dp [0] [0] [0] = 0;
	FOR(i,0,N) FOR(j,0,gx + 1) FOR(k,0,gy + 1) if(dp [i] [j] [k] < INF){
		chmin(dp [i + 1] [j] [k],dp [i] [j] [k]);
		if(j + X [i] <= gx && k + Y [i] <= gy){
			chmin(dp [i + 1] [j + X [i]] [k + Y [i]],dp [i] [j] [k] + C [i]);
		}
	}

	int ans = INF;
	FOR(i,0,gx + 1) FOR(j,0,gy + 1){
		chmin(ans,dp [N] [i] [j] + (gx - i) * F + (gy - j) * F);
	}

	printf("%d\n",ans);

	return 0;
}