#include <bits/stdc++.h>
using namespace std;
// macros
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> lll;
typedef tuple<int, int, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vll;
typedef vector<lll> vlll;
#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define RE(a,c) REP(a,0,c)
#define RE1(a,c) REP(a,1,c+1)
#define REI(a,b,c) REP(a,b,c+1)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define FOR(a,b) for(auto& a : b)
#define all(a) a.begin(), a.end()
#define INF 1e9
#define EPS 1e-9
#define pb push_back
#define popb pop_back
#define fi first
#define se second
#define sz size()
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
// input
template<class T> void IN(T& x) {cin >> x;}
template<class H, class... T> void IN(H& h, T&... t) {IN(h); IN(t...); }
// output
template<class T1, class T2> void OUT(const pair<T1,T2>& x);
template<class T> void OUT(const T& x) {cout << x;}
template<class H, class... T> void OUT(const H& h, const T&... t) {OUT(h); OUT(t...); }
template<class T1, class T2> void OUT(const pair<T1,T2>& x) {OUT(x.fi,' ',x.se);}
template<class... T> void OUTL(const T&... t) {OUT(t..., "\n"); }
template<class H> void OUTLS(const H& h) {OUTL(h); }
template<class H, class... T> void OUTLS(const H& h, const T&... t) {OUT(h,' '); OUTLS(t...); }
//===================//
// Added libraries //
//===================//
//===================//
//end added libraries//
//===================//
void program();
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
program();
}
//===================//
// begin program //
//===================//
const int MX = 5e5;
int n, m=0;
int a[MX], b[MX];
int rev[MX];
vi adj[MX];
int p[MX];
string s;
int dp[MX];
int sm[MX], skip[MX];
int getAns(int e);
int getSum(int e) {
int p=a[e], u=b[e];
if(sm[u] == -1) {
sm[u] = 0;
FOR(v,adj[u]) if(b[v] != p) sm[u] += getAns(v);
skip[u] = p;
} else if(skip[u] != -1 && skip[u] != p) {
FOR(v,adj[u]) if(b[v] == skip[u]) sm[u] += getAns(v);
skip[u] = -1;
}
int res = sm[u];
if(skip[u] != p) res -= getAns(rev[e]);
return res;
}
int getAns(int e) {
if(dp[e] != -1) return dp[e];
int p=a[e], u=b[e];
dp[e] = 0;
if(s[u]) {
dp[e] = getSum(e)-1;
dp[e] = max(dp[e], 1);
} else {
dp[e] = getSum(e);
}
return dp[e];
}
void program() {
IN(n);
RE(i,n-1) {
int u, v;
IN(u,v); u--; v--;
a[m] = u; b[m] = v; rev[m] = m+1;
adj[u].pb(m++);
a[m] = v; b[m] = u; rev[m] = m-1;
adj[v].pb(m++);
}
IN(s); RE(i,n) s[i]-='0';
RE(i,m) dp[i] = sm[i] = -1;
int ans = 0;
RE(u,n) {
if(!s[u]) continue;
ans = max(ans, 1);
FOR(v,adj[u]) ans = max(ans, 1+getAns(v));
}
OUTL(ans);
}
