#include<iostream>
#include<cstdio>
#define Rg register
#define il inline
#define db double
#define inf 200000001
#define int long long
#define go(i,a,b) for(Rg int i=a;i<=b;i++)
#define yes(i,a,b) for(Rg int i=a;i>=b;i--)
using namespace std;
il int read()
{int x=0,y=1;char c=getchar();while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();}while(c>='0'&&c<='9'){x=(x<<3)+(x<<1)+c-'0';c=getchar();}return x*y;
}
const int N=2001,M=301;
int m,n,v,e,c[N],d[N],dis[M][M];
db f[N][N][2],p[N],ans=inf;
void Read()
{n=read(),m=read(),v=read(),e=read();go(i,1,v) go(j,1,v)if(i!=j)dis[i][j]=inf;go(i,1,n)c[i]=read(); go(i,1,n)d[i]=read(); go(i,1,n)scanf("%lf",&p[i]);go(i,1,e){int x=read(),y=read();dis[x][y]=dis[y][x]=min(dis[x][y],read());}
}
void Floyed()
{go(k,1,v) go(j,1,v) go(i,1,j)if(dis[i][k]+dis[k][j]<dis[i][j])dis[i][j]=dis[j][i]=dis[i][k]+dis[k][j];
}
main()
{Read();Floyed();go(i,0,n) go(j,0,n)f[i][j][0]=f[i][j][1]=f[j][i][0]=f[j][i][1]=inf;f[1][0][0]=f[1][1][1]=0;go(i,2,n){int maxn=min(i,m);go(j,0,maxn){f[i][j][0]=min((db)(f[i-1][j][0]+dis[c[i-1]][c[i]]),(db)(f[i-1][j][1]+dis[d[i-1]][c[i]]*p[i-1]+dis[c[i-1]][c[i]]*(1-p[i-1])));if(j>0)f[i][j][1]=min((db)(f[i-1][j-1][0]+dis[c[i-1]][d[i]]*p[i]+dis[c[i-1]][c[i]]*(1-p[i])),(db)(f[i-1][j-1][1]+dis[c[i-1]][c[i]]*(1-p[i-1])*(1-p[i])+dis[c[i-1]][d[i]]*(1-p[i-1])*p[i]+dis[d[i-1]][c[i]]*(1-p[i])*p[i-1]+dis[d[i-1]][d[i]]*p[i-1]*p[i]));}}go(i,0,m)ans=min(min(f[n][i][0],f[n][i][1]),ans);printf("%.2lf",ans);return 0;
}