1 #include<bits/stdc++.h>
 2 #define pa pair<int,int>
 3 #define lowb(x) ((x)&(-(x)))
 4 #define REP(i,n0,n) for(i=n0;i<=n;i++)
 5 #define PER(i,n0,n) for(i=n;i>=n0;i--)
 6 #define MAX(a,b) ((a>b)?a:b)
 7 #define MIN(a,b) ((a<b)?a:b)
 8 #define CLR(a,x) memset(a,x,sizeof(a))
 9 #define rei register int
10 using namespace std;
11 typedef long long ll;
12 const int maxn=2020,maxm=2020,maxv=310;
13
14 inline ll rd(){
15     ll x=0;char c=getchar();int neg=1;
16     while(c<'0'||c>'9'){if(c=='-') neg=-1;c=getchar();}
17     while(c>='0'&&c<='9') x=x*10+c-'0',c=getchar();
18     return x*neg;
19 }
20
21 int N,M,V,E;
22 int pos[maxn][2],dis[maxn][maxn];
23 int sum[maxn];
24 double f[maxn][maxn][2],c[maxn];
25
26 void floyd(){
27     for(int i=1;i<=V;i++) dis[i][i]=0;
28     for(int i=1;i<=V;i++){
29         for(int j=1;j<=V;j++){
30             for(int k=1;k<=V;k++){
31                 if(dis[j][i]>=1e9||dis[i][k]>=1e9) continue;
32                 dis[j][k]=min(dis[j][i]+dis[i][k],dis[j][k]);
33             }
34         }
35     }
36 }
37
38 int main(){
39     //freopen(".in","r",stdin);
40     int i,j,k;
41     N=rd(),M=rd(),V=rd(),E=rd();
42     if(N==1){printf("0.00\n");return 0;}
43     for(i=1;i<=N;i++) pos[i][0]=rd();
44     for(i=1;i<=N;i++) pos[i][1]=rd();
45     for(i=1;i<=N;i++) scanf("%lf",&c[i]);
46     memset(dis,127,sizeof(dis));
47     for(i=1;i<=E;i++){
48         int a=rd(),b=rd(),c=rd();
49         dis[a][b]=min(dis[a][b],c);
50         dis[b][a]=min(dis[b][a],c);
51     }floyd();
52     for(i=1;i<=N;i++) for(j=0;j<=M;j++) f[i][j][0]=f[i][j][1]=1e9;
53     f[1][0][0]=f[1][1][0]=f[1][1][1]=0;
54     for(i=2;i<=N;i++){
55         for(j=0;j<=min(i,M);j++){
56             f[i][j][0]=min(f[i-1][j][0]+dis[pos[i-1][0]][pos[i][0]],
57                            f[i-1][j][1]+dis[pos[i-1][0]][pos[i][0]]*(1-c[i-1])+dis[pos[i-1][1]][pos[i][0]]*c[i-1]);
58             if(j){
59                 f[i][j][1]=min(f[i-1][j-1][0]+dis[pos[i-1][0]][pos[i][0]]*(1-c[i])+dis[pos[i-1][0]][pos[i][1]]*c[i],
60                                f[i-1][j-1][1]+(dis[pos[i-1][0]][pos[i][0]]*(1-c[i])+dis[pos[i-1][0]][pos[i][1]]*c[i])*(1-c[i-1])+
61                                               (dis[pos[i-1][1]][pos[i][0]]*(1-c[i])+dis[pos[i-1][1]][pos[i][1]]*c[i])*c[i-1]);
62             }
63         }
64     }
65     double ans=1e9;
66     for(i=0;i<=M;i++) ans=min(ans,min(f[N][i][0],f[N][i][1]));
67     printf("%.2lf\n",ans);
68     return 0;
69 }