#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;
const int N = 200'010;
int if_is_root[N];
bool has_gen[N];
vector<int> A[N];
int n;
int add_root_gen(int x, int rt)
{
if (has_gen[rt])
return max(x-1, 1);
else
return x;
}
void dfs1(int v, int p)
{
int sum = 0;
for (int u : A[v]) {
if (u == p)
continue;
dfs1(u, v);
sum += add_root_gen(if_is_root[u], u);
}
if_is_root[v] = sum;
}
int ans = 2;
void dfs2(int v, int p, int from_p)
{
int sum = from_p;
for (int u : A[v]) {
if (u == p)
continue;
sum += add_root_gen(if_is_root[u], u);
}
ans = max(ans, add_root_gen(sum, v));
for (int u : A[v]) {
if (u == p)
continue;
int from_u = add_root_gen(if_is_root[u], u);
dfs2(u, v, add_root_gen(sum - from_u, v));
}
}
void handle_edge()
{
int cnt = 0;
Loop (i,0,n)
cnt += has_gen[i];
if (cnt <= 2) {
cout << cnt << '\n';
exit(0);
}
}
int main()
{
cin.tie(0) -> sync_with_stdio(false);
cin >> n;
Loop (i,1,n) {
int v, u;
cin >> v >> u;
--v; --u;
A[v].push_back(u);
A[u].push_back(v);
}
string s;
cin >> s;
Loop (i,0,n)
has_gen[i] = s[i]-'0';
handle_edge();
dfs1(0, -1);
dfs2(0, -1, 0);
cout << ans << '\n';
}
