#include <bits/stdc++.h>
using namespace std;
// Power - subtask 2
#define ll long long
#define ull unsigned LL
#define ld long double
#define debug if(0)
#define fastio ios_base::sync_with_stdio(0); cin.tie()
const int N = 2e5 + 4;
string s;
vector<int> V[N], dp(N, 0);
bool vis[N];
void clear(int n) {
for(int i=1; i<=n; i++) {
dp[i] = 0;
vis[i] = 0;
}
}
void dfs(int v, int root) {
vis[v] = 1;
dp[v] = s[v-1] - '0';
int rb = 0, rc = 0;
for(int i=0; i<(int) V[v].size(); i++) {
int u = V[v][i];
if(!vis[u]) {
dfs(u, root);
rb += dp[u];
rc = max(rc, dp[u]);
}
}
if(v == root)
dp[v] = rc + 1;
else {
rb -= s[v-1] - '0';
dp[v] = max(dp[v], rb);
}
debug cerr<<"dp["<<v<<"] = "<<dp[v]<<"\n";
}
int main() {
fastio;
int n;
cin>>n;
for(int i=0; i<(n-1); i++) {
int a, b;
cin>>a>>b;
V[a].push_back(b);
V[b].push_back(a);
}
cin>>s;
int ans = 0;
for(int i=1; i<=n; i++) {
if(s[i-1] == '1') {
clear(n);
dfs(i, i);
ans = max(ans, dp[i]);
}
}
cout<<ans;
}
