#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;

class Graph{
	private:
	int V;
	vvp List;
	public:
	Graph(int v){
		V=v;
		List=vvp(v);
	}
	void add_edge(int s,int t,int c){
		List[s].push_back(P(t,c));
	}
	int DIJ(int s,int t){
		priority_queue<P> que;
		vi d(V,inf);
		d[s]=0;
		que.push(P(0,s));
		while(!que.empty()){
			P p=que.top();
			que.pop();
			int v=p.second;
			if(d[v]<-p.first) continue;
			for(int i=0;i<List[v].size();i++){
				int F=List[v][i].first,S=List[v][i].second;
				if(d[F]>d[v]+S){
					d[F]=d[v]+S;
					que.push(P(-d[F],F));
				}
			}
		}
		return d[t];
	}
};

int gx,gy,n,f;

int main(){
	cin>>gx>>gy>>n>>f;
	Graph g(e*e);
	for(int i=0;i<n;i++){
		int x,y,c;
		cin>>x>>y>>c;
		for(int j=0;j<e;j++) for(int k=0;k<e;k++){
			int cx=j+x,cy=k+y;
			if(cx>=0&&cx<e&&cy>=0&&cy<=e) g.add_edge(j*e+k,cx*e+cy,c);
		}
	}
	for(int i=0;i<e;i++) for(int j=0;j<e;j++){
		if(i!=e-1) g.add_edge(i*e+j,(i+1)*e+j,f);
		if(j!=e-1) g.add_edge(i*e+j,i*e+j+1,f);
	}
	cout<<g.DIJ(0,gx*e+gy)<<endl;
}