#pragma GCC optimize("O2")
#include <bits/stdc++.h>
#ifdef DEBUG
#include "debug.hpp"
#endif
using namespace std;
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define traverse(c, it) for(auto it = (c).begin(); it != (c).end(); ++it)
#define rep(i, N) for(int i = 0; i < (N); ++i)
#define rrep(i, N) for(int i = (N) - 1; i >= 0; --i)
#define rep1(i, N) for(int i = 1; i <= (N); ++i)
#define rep2(i, s, e) for(int i = (s); i <= (e); ++i)
#define rep3(i, s, e, d) for(int i = (s); (d) >= 0 ? i <= (e) : i >= (e); i += (d))
#ifdef DEBUG
#define debug(x...) { \
++dbg::depth; \
string dbg_vals = dbg::to_string(x); \
--dbg::depth; \
dbg::fprint(__func__, __LINE__, #x, dbg_vals); \
}
#define light_debug(x) { \
dbg::light = true; \
dbg::dout << __func__ << ":" << __LINE__; \
dbg::dout << " " << #x << " = " << x << endl; \
dbg::light = false; \
}
#else
#define debug(x...) 42
#define light_debug(x) 42
#endif
using ll = long long;
template<typename T>
inline T& ckmin(T& a, T b) { return a = a > b ? b : a; }
template<typename T>
inline T& ckmax(T& a, T b) { return a = a < b ? b : a; }
template<class Fun>
class y_combinator_result {
Fun fun_;
public:
template<class T>
explicit y_combinator_result(T &&fun): fun_(std::forward<T>(fun)) {}
template<class ...Args>
decltype(auto) operator()(Args &&...args) {
return fun_(std::ref(*this), std::forward<Args>(args)...);
}
};
template<class Fun>
decltype(auto) y_combinator(Fun &&fun) {
return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
#ifdef DEBUG
freopen("debug", "w", stderr);
#endif
int n; cin >> n;
vector<vector<int>> adj(n);
vector<int> dp_0(n), dp_1(n);
rep(_, n - 1) {
int a, b; cin >> a >> b; --a, --b;
adj[a].push_back(b), adj[b].push_back(a);
}
string s; cin >> s;
y_combinator([&](auto dfs, int v, int p) -> void {
for(int u : adj[v]) if(u != p) dfs(u, v);
int t{}, g{s[v] == '1'};
dp_1[v] = g;
for(int u : adj[v]) if(u != p)
t += dp_1[u];
ckmax(dp_1[v], t - g);
dp_0[v] = dp_1[v];
for(int u : adj[v]) if(u != p)
ckmax(dp_0[v], max(dp_0[u], g + dp_1[u]));
})(0, -1);
cout << dp_0[0] << '\n';
#ifdef DEBUG
dbg::dout << "\nExecution time: " << clock() * 1000 / CLOCKS_PER_SEC << "ms" << endl;
#endif
return 0;
}
