#include<bits/stdc++.h>
#define FILE "read"
#define MAXN 2010
#define cmax(a,b) a=max(a,b)
#define cmin(a,b) a=min(a,b)
using namespace std;
int n,m,v,e,c[MAXN],d[MAXN],dis[305][305];
double ans,f[MAXN][MAXN][2],p[MAXN];
inline int read(){
	int x=0,f=1;  char ch=getchar();
	while(!isdigit(ch))  {if(ch=='-')  f=-1;  ch=getchar();}
	while(isdigit(ch))  {x=x*10+ch-'0';  ch=getchar();}
	return x*f;
}
void print(){
	for(int i=1;i<=v;++i){
		for(int j=1;j<=v;++j)
			printf("%d ",dis[i][j]);
		printf("\n");
	}
}
int main(){
	freopen(FILE".in","r",stdin);
	freopen(FILE".out","w",stdout);
	n=read();  m=read();  v=read();  e=read();
	for(int i=1;i<=n;++i)  c[i]=read();
	for(int i=1;i<=n;++i)  d[i]=read();
	for(int i=1;i<=n;++i)  scanf("%lf",&p[i]);
	memset(dis,10,sizeof(dis));
	for(int i=1;i<=e;++i){
		int x=read(),y=read(),v=read();
		cmin(dis[x][y],v);  cmin(dis[y][x],v);
	}
	for(int i=1;i<=v;++i)  dis[i][i]=0;
	for(int k=1;k<=v;++k)
		for(int i=1;i<=v;++i)
			for(int j=1;j<=v;++j)
				if(dis[i][k]+dis[k][j]<dis[i][j]) dis[i][j]=dis[i][k]+dis[k][j];
	for(int i=1;i<=v;++i)  dis[0][i]=0;
	for(int i=0;i<=n;++i) for(int j=0;j<=n;++j) for(int k=0;k<=1;++k) f[i][j][k]=1e9;
	f[1][0][0]=f[1][1][1]=0;  ans=1e9;
	for(int i=2;i<=n;++i)
		for(int j=0;j<=m;++j){
			f[i][j][0]=min(f[i-1][j][0]+dis[c[i]][c[i-1]],f[i-1][j][1]+dis[c[i]][c[i-1]]*(1-p[i-1])+dis[c[i]][d[i-1]]*p[i-1]);
			if(j>=1) f[i][j][1]=min(f[i-1][j-1][0]+dis[d[i]][c[i-1]]*p[i]+dis[c[i]][c[i-1]]*(1-p[i]),
			f[i-1][j-1][1]+dis[c[i]][d[i-1]]*p[i-1]*(1-p[i])+dis[c[i]][c[i-1]]*(1-p[i])*(1-p[i-1])+dis[d[i]][c[i-1]]*p[i]*(1-p[i-1])+dis[d[i]][d[i-1]]*p[i]*p[i-1]);
		}
	for(int i=0;i<=m;++i)for(int j=0;j<=1;++j)cmin(ans,f[n][i][j]);
	printf("%.2lf\n",ans);
	return 0;
}