//minamoto

 #include<iostream>

 #include<cstdio>

 #include<cstring>

 #define inf 1e17

 using namespace std;

 template<class T>inline bool cmin(T&a,const T&b){return a>b?a=b,:;}

 inline int read(){

     #define num ch-'0'

     char ch;bool flag=;int res;

     while(!isdigit(ch=getchar()))

     (ch=='-')&&(flag=true);

     for(res=num;isdigit(ch=getchar());res=res*+num);

     (flag)&&(res=-res);

     #undef num

     return res;

 }

 const int N=,M=;

 int mp[M][M],c[N][],n,m,e,v;double dp[N][N][],k[N],ans;

 int main(){

 //    freopen("testdata.in","r",stdin);

     memset(mp,0x3f,sizeof(mp));

     n=read(),m=read(),v=read(),e=read();

     for(int i=;i<=n;++i) c[i][]=read();

     for(int i=;i<=n;++i) c[i][]=read();

     for(int i=;i<=n;++i) scanf("%lf",&k[i]);

     for(int i=,u,v,w;i<=e;++i){

         u=read(),v=read(),w=read();

         cmin(mp[u][v],w),cmin(mp[v][u],w);

     }

     for(int i=;i<=v;++i) mp[i][i]=mp[i][]=mp[][i]=;

     for(int k=;k<=v;++k) for(int i=;i<=v;++i) for(int j=;j<=v;++j)

     cmin(mp[i][j],mp[i][k]+mp[k][j]);

     for(int i=;i<=n;++i) for(int j=;j<=m;++j) dp[i][j][]=dp[i][j][]=inf;

     dp[][][]=dp[][][]=;

     for(int i=;i<=n;++i){

         dp[i][][]=dp[i-][][]+mp[c[i][]][c[i-][]];

         for(int j=,l=min(i,m);j<=l;++j){

             int c1=c[i][],c2=c[i][],c3=c[i-][],c4=c[i-][];

             cmin(dp[i][j][],dp[i-][j][]+mp[c1][c3]);

             cmin(dp[i][j][],dp[i-][j][]+mp[c1][c4]*k[i-]+mp[c1][c3]*(-k[i-]));

             cmin(dp[i][j][],dp[i-][j-][]+mp[c1][c3]*(-k[i])+mp[c2][c3]*k[i]);

             cmin(dp[i][j][],dp[i-][j-][]+mp[c1][c3]*(-k[i-])*(-k[i])+

             mp[c2][c3]*(-k[i-])*k[i]+mp[c1][c4]*k[i-]*(-k[i])+mp[c2][c4]*k[i-]*k[i]);

         }

     }

     ans=inf;

     for(int i=;i<=m;++i) cmin(ans,dp[n][i][]),cmin(ans,dp[n][i][]);

     printf("%.2lf\n",ans);

     return ;

 }