#include <bits/stdc++.h>
using namespace std;
const int mxn = 2e5+5;
typedef long long ll;
typedef unsigned int ui;
typedef unsigned long long ull;
typedef pair<int,int>pii;
typedef pair<int,pii>piii;
#define sf scanf
#define pf printf
#define input freopen("in.txt","r",stdin)
#define output freopen("out.txt","w",stdout)
#define inf 1e18
#define ff first
#define ss second
#define MP make_pair
#define pb push_back
#define all(v) v.begin(), v.end()
#define printcase(cases) printf("Case %d:", cases);
#define Unique(a) a.erase(unique(a.begin(),a.end()),a.end())
#define FAST ios_base::sync_with_stdio(0);cout.tie(0)
#define endl printf("\n")
#define __lcm(a, b) ((a*b)/__gcd(a, b))
int arr[mxn];
vector<int>adj[mxn];
int dp[mxn];
int ans = 0;
void dfs(int u, int p)
{
int mx = 0;
for(auto v : adj[u])
{
if(v==p) continue;
dfs(v, u);
dp[u]+=dp[v];
mx = max(mx, dp[v]);
}
if(arr[u])
{
ans = max(ans, mx+1);
dp[u] = max(1, dp[u]-1);
}
ans = max(ans, dp[u]);
}
int main()
{
// input;
//output;
int n;
cin >> n;
for(int i = 1; i < n; i++)
{
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
string s;
cin >> s;
for(int i = 0; i < n; i++) arr[i+1] = s[i]-'0';
dfs(1, 1);
cout << ans << '\n';
return 0;
}
