#include <bits/stdc++.h>
using namespace std;
const int N=2e5+5;
int n,x,y,res;
int a[N],down[N],save_sum[N];
char c;
vector <int> adj[N];
void pre_dfs(int u,int par)
{
int sum=0;
for (int v:adj[u])
if (v!=par)
{
pre_dfs(v,u);
sum+=down[v];
}
save_sum[u]=sum;
if (a[u]==0) down[u]=sum;
else down[u]=max(sum-1,1);
res=max(res,down[u]);
}
void dfsOne(int u,int par,int ma)
{
res=max(res,save_sum[u]+ma-a[u]);
for (int v:adj[u])
if (v!=par)
dfsOne(v,u,max(a[u],ma+save_sum[u]-down[v]-a[u]));
}
int main()
{
ios_base::sync_with_stdio(NULL);
cin.tie(NULL); cout.tie(NULL);
cin >> n;
for (int i=1;i<n;i++)
{
cin >> x >> y;
adj[x].push_back(y);
adj[y].push_back(x);
}
res=0;
for (int i=1;i<=n;i++)
{
cin >> c;
a[i]=c-'0';
res+=a[i];
}
res=min(res,2);
pre_dfs(1,-1);
dfsOne(1,-1,0);
cout << res;
}
