#include <bits/stdc++.h>
#define fi first
#define si second
#define For(i,a,b) for (int i = (a), _b =(b); i <= _b; ++i)
#define all(v) v.begin(), v.end()
#define Unique(v) v.erase(unique(all(v)), v.end())
#define MASK(i) (1LL << (i))
#define bit(i,n) (((n)>>(i)) & 1)
#define Vii vector<pair<int,int>>
#define setpr(x) cout<<setprecision(x)<<fixed
#define Prior priority_queue< pair<int,int> , Vii, greater<Pair> >
using namespace std;
const int Mod = 1E9 + 7;
const long long INF = 4E18;
const int N = 2e5 + 1;
int n,dp[N],ans = 0,a[N];
vector<int> g[N];
void dfs(int u, int p)
{
int maxx = 0;
for(int v : g[u]) if(v != p)
{
dfs(v,u);
dp[u] += dp[v];
maxx = max(dp[v],maxx);
}
if(a[u]) dp[u] = max(dp[u]-1,1);
ans = max({dp[u],ans,maxx + a[u]});
}
signed main(){
cin >> n;
For(i,2,n)
{
int u,v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
string s;
cin >> s;
for(int i = 0; i < n; i++) a[i+1] = s[i]-'0';
dfs(1,0);
cout << ans;
}
