#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
#define FOR(i, x, y) for(ll i=x; i<y; i++)
#define FORNEG(i, x, y) for(ll i=x; i>y; i--)
#define fast() ios_base::sync_with_stdio(false);cin.tie(NULL)
ll n;
string sus;
vector<ll> edges[200001];
ll par[200001];
bool visited[200001];
ll dps[200001];
ll ans = 0;
void dfs(ll a){
for (auto&i : edges[a]){
if (!visited[i]){
visited[i] = true;
par[i] = a;
dfs(i);
}
}
}
ll dp(ll a){
if (dps[a] != -1) return dps[a];
ll sum = 0;
ll maxi = 0;
for (auto&i : edges[a]){
if (i==par[a]) continue;
sum += dp(i);
maxi = max(maxi, dp(i));
}
if (sus[a-1] == '1'){
ans = max(ans, max(maxi+1, sum-1));
}else{
ans = max(ans, sum);
}
dps[a] = max(sum - sus[a-1] + '0', ll(sus[a-1] - '0'));
return max(sum - sus[a-1] + '0', ll(sus[a-1] - '0'));
}
int main(){
cin >> n;
if (n==1){
cout << 1;
return 0;
}
FOR(i,0,n-1){
ll a,b;
cin >> a >> b;
edges[a].push_back(b);
edges[b].push_back(a);
}
cin >> sus;
FOR(i,0,n+1) par[i] = -1, visited[i] = 0, dps[i] = -1;
visited[1] = true;
dfs(1);
dp(1);
cout << ans;
}
