// author: erray
#include <bits/stdc++.h>
using namespace std;
template<typename A, typename B> string to_string(const pair<A, B>& p);
template<typename A, typename B, typename C> string to_string(const tuple<A, B, C>& t);
template<typename A, typename B, typename C, typename D> string to_string(const tuple<A, B, C, D>& t);
string to_string(const string& s) {
return '"' + s + '"';
}
string to_string(const char& c) {
return "'"s + c + "'";
}
string to_string(const char *c) {
return to_string(string(c));
}
string to_string(const bool& b) {
return (b ? "true" : "false");
}
string to_string(const vector<bool>& v) {
string res = "{";
for (int i = 0; i < (int) v.size(); ++i) {
if (i > 0) {
res += ", ";
}
res += to_string(v[i]);
}
res += "}";
return res;
}
template<size_t T> string to_string(const bitset<T>& bs) {
return bs.to_string();
}
template<typename T> string to_string(queue<T> q) {
string res = "{";
size_t sz = q.size();
while (sz--) {
T cur = q.front();
q.pop();
q.push(cur);
if ((int) res.size() > 1) {
res += ", ";
}
res += to_string(cur);
}
res += "}";
return res;
}
template<typename T, class C> string to_string(priority_queue<T, vector<T>, C> pq) {
vector<T> tmp;
string res = "{";
while (!pq.empty()) {
T cur = pq.top();
pq.pop();
if ((int) res.size() > 1) {
res += ", ";
}
res += to_string(cur);
tmp.push_back(cur);
}
for (auto el : tmp) {
pq.push(el);
}
res += "}";
return res;
}
template<typename T> string to_string(const T& v) {
string res = "{";
for (auto &el : v) {
if ((int) res.size() > 1) {
res += ", ";
}
res += to_string(el);
}
res += "}";
return res;
}
template<typename A, typename B> string to_string(const pair<A, B>& p) {
return '(' + to_string(p.first) + ", " + to_string(p.second) + ')';
}
template<typename A, typename B, typename C> string to_string(const tuple<A, B, C>& t) {
return '(' + to_string(get<0>(t)) + ", " + to_string(get<1>(t)) + ", " + to_string(get<2>(t)) + ')';
}
template<typename A, typename B, typename C, typename D> string to_string(const tuple<A, B, C, D>& t) {
return '(' + to_string(get<0>(t)) + ", " + to_string(get<1>(t)) + ", " + to_string(get<2>(t)) + ", " + to_string(get<3>(t)) + ')';
}
void debug_out(int size, bool first, string name) {
vector<string> tmp = {name};
vector<int> tmp2 = {size, first};
cerr << endl;
}
constexpr int buffer_size = 255;
template<typename Head, typename... Tail> void debug_out(int size, bool first, string name, Head H, Tail... T) {
string tmp;
int off = 0;
while ((!name.empty() && name[0] != ',') || off != 0) {
tmp += name[0];
name.erase(name.begin());
char c = tmp.back();
if (c == '{' || c == '(') {
++off;
} else if (c == '}' || c == ')'){
--off;
}
}
if (!name.empty()) {
name.erase(name.begin());
}
if (tmp[0] == ' ') {
tmp.erase(tmp.begin());
}
string buff = to_string(H);
if ((int) buff.size() + size + (int) tmp.size() > buffer_size - 5 && !first) {
cerr << '\n';
size = 0;
}
cerr << '[' << tmp << ": " << buff << "] ";
debug_out(((int) buff.size() + size + (int) tmp.size() + 5) % buffer_size, false, name, T...);
}
#ifdef DEBUG
#define debug(...) cerr << "-> ", debug_out(3, true, string(#__VA_ARGS__), __VA_ARGS__)
#define here cerr << "-> " << __LINE__ << endl
#else
#define debug(...) void(37)
#define here void(37)
#endif
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
vector<vector<int>> g(n);
for (int i = 0; i < n - 1; ++i) {
int x, y;
cin >> x >> y;
--x, --y;
g[x].push_back(y);
g[y].push_back(x);
}
string s;
cin >> s;
vector<vector<int>> dp(n, vector<int>(2));
function<void(int, int)> Dfs = [&](int v, int pr) {
vector<int> on(2, s[v] - '0'), off(2, -(s[v] - '0'));
for (auto u : g[v]) {
if (u == pr) {
continue;
}
Dfs(u, v);
off[0] += dp[u][1];
off[1] += dp[u][1];
if (s[v] == '1') {
on[0] = max(on[0], dp[u][1] + 1);
on[1] = 1;
}
}
dp[v][0] = max(on[0], off[0]);
dp[v][1] = max(on[1], off[1]);
debug(v, dp[v]);
};
Dfs(0, -1);
debug(dp);
int ans = 0;
for (int i = 0; i < n; ++i) {
ans = max(ans, dp[i][0]);
}
cout << ans << '\n';
}
