#include <iostream>
#include <fstream>
#include <typeinfo>
#include <vector>
#include <stack>
#include <cmath>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <cstdio>
#include <queue>
#include <iomanip>
#include <cctype>
#include <random>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<string> vs;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<29;
const ll INF=1ll<<52;
const double pi=acos(-1);
const double eps=1e-8;
const ll mod=1e9+7;
const int dx[4]={0,1,0,-1},dy[4]={1,0,-1,-0};
const int DX[8]={-1,-1,-1,0,1,1,1,0},DY[8]={1,0,-1,-1,-1,0,1,1};

const int e=101;

int gx,gy,n,f;

int main(){
	cin>>gx>>gy>>n>>f;
	vvi dp(e,vi(e,inf));
	dp[0][0]=0;
	for(int i=0;i<n;i++){
		int x,y,c;
		cin>>x>>y>>c;
		for(int j=e-1;j>=0;j--) for(int k=e-1;k>=0;k--){
			int cx=j-x,cy=k-y;
			if(cx>=0&&cy>=0) dp[j][y]=min(dp[j][k],dp[cx][cy]+c);
		}
	}
	int ans=(gx+gy)*f;
	for(int i=0;i<e;i++) for(int j=0;j<e;j++) if(dp[i][j]){
		ans=min(ans,dp[i][j]+(abs(i-gx)+abs(j-gy))*f);
	}
	cout<<ans<<endl;
}