#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define int ll
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define REP(i, n) FOR(i, 0, n)
#define REP1(i, n) FOR(i, 1, n+1)
#define pii pair<int, int>
#define f first
#define s second
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) (int)((x).size())
#define pb push_back
#define endl '\n'
#define IOS() ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
const ll maxn = 2e5+5;
const ll inf = 1ll<<60;
const ll mod = 1e9+7;
int n;
int ans = 1;
vector<int> dp(maxn);
vector<int> g[maxn];
vector<int> c(maxn);
void dfs(int x, int pre){
int tp = (x > 1 && c[pre]);
for (auto y:g[x]){
if (y == pre) continue;
dfs(y, x);
dp[x] += max((int)(c[y]), dp[y]);
}
dp[x] -= c[x];
ans = max(ans, dp[x]+tp);
}
signed main(){
IOS();
cin>>n;
REP(i, n-1){
int u, v; cin>>u>>v;
g[u].pb(v);
g[v].pb(u);
}
string str; cin>>str;
str = '$'+str;
REP1(i, n) c[i] = (str[i] == '1');
REP1(i, n){
for (auto y:g[i]) ans = max(ans, c[i]+c[y]);
}
dfs(1, -1);
cout<<ans<<endl;
}
