#include <bits/stdc++.h>
using namespace std;
#define int long long
//#define all(x) x.begin(),x.end()
//#define rall(x) x.rbegin(),x.rend()
//#define ff first
//#define ss second
//#define pb push_back
//template<class T, class U> inline bool chmin(T& a, const U& b) { if (a > b) { a = b; return true; } return false; }
//template<class T, class U> inline bool chmax(T& a, const U& b) { if (a < b) { a = b; return true; } return false; }
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//#define rnd(l, r) uniform_int_distribution <int> (l, r)(rng)
const int inf = 1e6, mod = 1e9 + 7;
void solve(){
int n;
cin >> n;
vector<vector<int>> g(n);
for(int i = 1; i < n; i++ ){
int a, b;
cin >> a >> b;
a--, b--;
g[a].push_back(b);
g[b].push_back(a);
};
string s;
cin >> s;
vector<int> dp(n, 0);
function< void(int,int) > dup = [&](int ps, int pr) {
for(int to : g[ps])
if(to != pr)
dup(to, ps);
int sum = 0;
for(int to : g[ps])
if(to != pr)sum += dp[to];
dp[ps] = (s[ps] == '1' ? 1 : 0);
dp[ps] = max(dp[ps], sum + (s[ps] == '1' ? -1 : 0));
};
dup(0, 0);
int ans = 0;
function< void(int,int,int) > dfs = [&](int ps, int pr, int up) {
int sum = up;
for(int to : g[ps])
if(to != pr)sum += dp[to];
ans = max(ans, dp[ps] + up);
for(int to : g[ps])
if(to != pr){
int res = (s[ps] == '1' ? 1 : 0);
res = max(res, sum - dp[to] + (s[ps] == '1' ? -1 : 0));
dfs(to, ps, res);
};
};
dfs(0, 0, 0);
cout << ans << '\n';
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);cout.tie(nullptr);
int tt = 1;
//cin >> tt;
while(tt--){
solve();
};
}
