#include<bits/stdc++.h> using namespace std; double k[2001],f[2001][2001][2]; int a[2001],b[2001],Map[301][301],n,m,v,e,i,j,x,y,z; int main(){ cin>>n>>m>>v>>e; for(i=1; i<=v; i++)for(j=1; j<=v; j++)i==j?Map[i][j]=0:Map[i][j]=2147483647; for(i=1; i<=n; i++) for(j=0; j<n; j++){ f[i][j][0]=2147483647; f[i][j][1]=2147483647; } f[1][0][0]=0; f[1][1][1]=0; for(i=1; i<=n; i++)cin>>a[i]>>b[i]>>k[i]; for(i=1; i<=e; i++){ cin>>x>>y>>z; if(Map[x][y]>z){ Map[x][y]=z; Map[y][x]=z; } } for(int o=1; o<=v; o++)for(i=1; i<=v; i++)for(j=1; j<=v; j++)if((Map[i][j]>Map[i][o]+Map[o][j])&&(Map[i][o]!=2147483647)&&(Map[o][j]!=2147483647))Map[i][j]=Map[i][o]+Map[o][j]; for(i=2; i<=n; i++)f[i][0][0]=f[i-1][0][0]+Map[a[i-1]][a[i]]; for(i=2; i<=n; i++) for(j=1; j<=min(m,i); j++){ f[i][j][0]=min(f[i-1][j][0] + Map[a[i-1]][a[i]],f[i-1][j][1] + Map[a[i-1]][a[i]]*(1.0-k[i-1])+Map[b[i-1]][a[i]]*k[i-1]); f[i][j][1]=min(f[i-1][j-1][0] + Map[a[i-1]][a[i]]*(1.0-k[i])+Map[a[i-1]][b[i]]*k[i],f[i-1][j-1][1]+ Map[a[i-1]][a[i]]*(1.0-k[i-1])*(1.0-k[i])+ Map[b[i-1]][a[i]]*k[i-1]*(1.0-k[i])+ Map[a[i-1]][b[i]]*(1.0-k[i-1])*(k[i])+ Map[b[i-1]][b[i]]*k[i-1]*k[i]); } double ans=f[n][0][0]; for(i=1; i<=m; i++){ if(f[n][i][0]<ans)ans=f[n][i][0]; if(f[n][i][1]<ans)ans=f[n][i][1]; } cout<<setprecision(2)<<fixed<<ans; return 0; }