#include<bits/stdc++.h>
#define TASKNAME "codeforce"
#define pb push_back
#define pli pair<int,int>
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL);
using namespace std;
using ll=long long;
const ll maxN=3e5;
const ll inf=1e18;
const ll mod=1e9+7;
ll ans=0;
vector<ll>g[maxN];
ll dp[maxN];
string s;
void dfs(ll u=1,ll p=0)
{
dp[u]=(s[u]=='1');
ll x=0;
for(int v:g[u])
{
if(v!=p)
{
dfs(v,u);
x+=dp[v];
//dp[u]=max(dp[u],dp[v]);
}
}
dp[u]=max(dp[u],x-(s[u]=='1'));
ans=max(ans,dp[u]);
for(int v:g[u])
{
if(v!=p)
{
ans=max(ans,dp[v]+(s[u]=='1'));
}
}
}
ll n;
void solve()
{
cin >> n;
for(int i=1;i<n;i++)
{
ll u,v;
cin >> u >> v ;
g[u].pb(v);
g[v].pb(u);
}
cin >> s;
s=' '+s;
dfs();
cout << ans;
}
int main()
{
fastio
//freopen(TASKNAME".INP","r",stdin);
//freopen(TASKNAME".OUT","w",stdout);
solve();
}
