#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; i++)
#define FORD(i, b, a) for (int i = (b), _a = (a); i >= _a; i--)
#define pa pair<ll, ll>
#define fi first
#define se second
#define bit(mask, j) ((mask >> j) & 1)
const ll mod = 1e9 + 7;
const ll INF = 1e18;
//--------------------------------------------------------------------
const ll N = 2e5 + 10;
ll n;
vector<ll> g[N];
ll h[N], up[N][20];
ll f[N], c[N];
ll in[N], en[N], m, sz[N], arr[N];
void dfs(ll u, ll p) {
f[u] += c[u];
in[u] = ++m;
arr[m] = u;
sz[u] = c[u];
for(auto v : g[u]) {
if(v == p) continue;
h[v] = h[u] + 1;
f[v] = f[u];
up[v][0] = u;
FOR(i, 1, 18) {
up[v][i] = up[up[v][i - 1]][i - 1];
}
dfs(v, u);
sz[u] += sz[v];
}
en[u] = m;
}
ll get(ll u, ll k) {
for(int j = 0; (1 << j) <= k; j++) {
if(bit(k, j)) u = up[u][j];
}
return u;
}
ll lca(ll u, ll v) {
if(h[u] < h[v]) swap(u, v);
u = get(u, h[u] - h[v]);
if(v == u) return u;
FORD(i, 18, 0) {
if(up[u][i] != up[v][i]) {
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
ll dist(ll u, ll v) {
ll p = lca(u, v);
return f[u] - f[v] + 2 * f[p] + c[p];
}
bool dx[N];
void dfs2(ll u, ll p, ll &cur) {
if(dx[u]) return;
cur += c[u];
for(auto v : g[u]) {
if(v == p) continue;
dfs2(v, u, cur);
}
}
void hbmt() {
cin >> n;
FOR(i, 1, n - 1) {
ll u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
ll cnt = 0;
FOR(i, 1, n) {
char x;
cin >> x;
c[i] = x - '0';
cnt += c[i];
}
ll ans = 0;
ans = min(cnt, 2LL);
if(cnt == 0) {
cout << 0;
return;
}
dfs(1, 0);
vector<ll> vt;
FOR(i, 1, n) {
ll u = arr[i];
if(c[u] == 1 && sz[u] <= 2) {
vt.push_back(u);
i = en[u];
}
}
sort(vt.begin(), vt.end(), [&] (ll &x, ll &y) {
return in[x] < in[y];
});
ll p = vt[0];
FOR(i, 1, vt.size() - 1) {
ll u = vt[i];
p = lca(p, u);
}
ll cur = sz[p];
dx[p] = 1;
FOR(i, 0, vt.size() - 1) {
ll u = vt[i];
cur -= sz[u];
}
ll sz = vt.size();
cur = sz - cur;
dfs2(1, 0, cur);
cout << max(ans, cur);
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
#define NAME "hbmt"
if(fopen(NAME".inp", "r")) {
freopen(NAME".inp", "r", stdin);
freopen(NAME".out", "w", stdout);
}
//int t;cin>>t;while(t--)
hbmt();
return 0;
}
