#include "bits/stdc++.h"
using namespace std;
#define ar array
//~ #define int long long
const int N = 2e5 + 5;
vector<int> edges[N];
int a[N], dp[N], res, up[N];
void dfs(int u, int p = -1){
for(auto x : edges[u]){
if(x == p) continue;
dfs(x, u);
dp[u] += dp[x];
}
dp[u] = max(dp[u] - a[u], a[u]);
}
void redfs(int u, int p = -1){
for(auto x : edges[u]){
if(x == p) continue;
up[x] += up[u];
up[u] += dp[x];
} up[u] = max(up[u] - a[u], a[u]);
res = max(up[u], res);
up[u] = 0;
reverse(edges[u].begin(), edges[u].end());
for(auto x : edges[u]){
if(x == p) continue;
up[x] += up[u];
up[u] += dp[x];
up[x] = max(up[x] - a[u], a[u]);
redfs(x, u);
}
}
signed main(){
ios::sync_with_stdio(0); cin.tie(0);
int n; cin>>n;
for(int i=1;i<n;i++){
int a, b; cin>>a>>b;
edges[a].push_back(b);
edges[b].push_back(a);
} for(int i=1;i<=n;i++){
char c; cin>>c;
a[i] = c - '0';
}
for(int i=1;i<=n;i++){
for(auto x : edges[i]){
if(a[x] && a[i]) res = 2;
}
}
dfs(1);
redfs(1);
cout<<res<<"\n";
}
