code:
#include <bits/stdc++.h>
#define N 500002
#define LL long long
#define setIO(s) freopen(s".in","r",stdin)
using namespace std;
int n,edges;
double f[N],g[N],perc[N<<1],q[N];
int hd[N],to[N<<1],nex[N<<1];
void add(int u,int v,double c)
{
nex[++edges]=hd[u],hd[u]=edges,to[edges]=v,perc[edges]=c;
}
void dfs1(int u,int ff)
{
f[u]=1-q[u];
for(int i=hd[u];i;i=nex[i])
{
int v=to[i];
if(v==ff) continue;
dfs1(v,u);
f[u]*=(1-perc[i]+perc[i]*f[v]);
}
}
void dfs2(int u,int ff,int j)
{
if(u==1) g[u]=f[u];
else
{
double p=g[ff]/(1-perc[j]+perc[j]*f[u]);
g[u]=f[u]*(1-perc[j]+perc[j]*p);
}
for(int i=hd[u];i;i=nex[i])
{
int v=to[i];
if(v==ff) continue;
dfs2(v,u,i);
}
}
int main()
{
// setIO("input");
int i,j;
scanf("%d",&n);
for(i=1;i<n;++i)
{
int x,y,z;
scanf("%d%d%d",&x,&y,&z),add(x,y,(double)z/100),add(y,x,(double)z/100);
}
for(i=1;i<=n;++i) scanf("%lf",&q[i]), q[i]/=100;
dfs1(1,0);
dfs2(1,0,0);
double ans=0;
for(i=1;i<=n;++i) ans+=1.0-g[i];
printf("%.6lf",ans);
return 0;
}