#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::steady_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
const int MAXN = 2e5 + 7;
vi g[MAXN];
int dp[MAXN];
string s;
int n;
int ans = 1;
void dfs(int v, int p){
dp[v] = (s[v - 1] - '0');
ans = max(ans, dp[v]);
int sum = 0;
int mx = 0;
for(auto u : g[v]){
if(u != p){
dfs(u, v);
mx = max(mx, dp[u]);
if(s[v - 1] == '0'){
dp[v] += dp[u];
}else{
sum += dp[u];
}
}
}
if(s[v - 1] == '1'){
dp[v] = max(1, sum - 1);
ans = max(ans, mx + 1);
}
//cout << v << ' ' << dp[v] << '\n';
ans = max(ans, dp[v]);
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
for(int i = 1; i < n; i++){
int u, v;
cin >> u >> v;
g[u].pb(v);
g[v].pb(u);
}
cin >> s;
ans = 1;
dfs(1, 1);
cout << ans << '\n';
return 0;
}
