//#pragma GCC optomize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("O3")
//#pragma GCC target("avx2")
//#pragma GCC target("sse,sse2,sse4.1,sse4.2")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define max_heap priority_queue<pair <ll, pair <ll, ll>>>
#define min_heap priority_queue<pair <ll, ll>, vector<pair <ll, ll>>, greater<pair <ll, ll>>>
//#define min_heap priority_queue<ll, vector<ll>, greater<ll>>
#define sariE cin.tie(NULL); cout.tie(NULL); ios_base::sync_with_stdio(false);
#define filE freopen("in.txt", "r", stdin); freopen("out1.txt", "w", stdout);
#define endl '\n'
#define md(a) (a % mod + mod) % mod
#define pb push_back
//cout << vectorprecision(5) << fixed << f;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll const maxn = 2e5 + 123;
ll const inf = 2e12;
ll const loG = 23;
ll const mod = 1e9 + 7;
//ll const mod = 998244353;
ll const sq = 350;
ll power(ll a, ll b, ll mod){if(b==0)return 1;if(b==1)return a;ll x = power(a, b / 2, mod);return (((x * x) % mod) * (b % 2 ? a : 1)) % mod;}
ll n, dp[maxn][2], col[maxn];
vector <ll> g[maxn];
void dfs(ll v, ll p){
ll mx0 = 0, mx1 = 0, sum0 = 0, sum1 = 0;
for (ll u : g[v]){
if (u != p){
dfs(u, v);
mx0 = max(mx0, dp[u][0]);
mx1 = max(mx1, dp[u][1]);
sum0 += max((ll)0, dp[u][0]);
sum1 += max((ll)0, dp[u][1]);
}
}
//cout << v << ' ' << col[v] << ' ' << sum0 << ' ' << mx1 << endl;
if (col[v]){
dp[v][0] = max(max(mx1 + 1, mx0), max((ll)1, sum1 - 1));
//dp[v][0] = max({(ll)1, sum0 - 1, mx1 + 1});
dp[v][1] = max((ll)1, sum1 - 1);
}
else{
dp[v][0] = max(sum1, mx0);
dp[v][1] = sum1;
}
}
string s;
void Solve(){
cin >> n;
for (int i = 1; i < n; i++){
ll a, b; cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
cin >> s;
s = ' ' + s;
for (int i = 1; i < n + 1; i++){
if (s[i] == '1')
col[i] = 1;
}
dfs(1, 1);
// for (int i = 1; i < n + 1; i++){
// cout << i << ' ' << col[i] << ' ' << dp[i][0] << ' ' << dp[i][1] << endl;
// }
cout << dp[1][0] << endl;
}
int main(){
sariE;// filE;
int test = 1;
//cin >> test;
while (test--) Solve();
return 0;
}
