#include<bits/stdc++.h>
using namespace std;
const int N = 200000 + 5;
vector <int> g[N];
int prelist[N], n;
string a;
int dfs(int node, int father)
{
int st = a[node-1] - '0', best_child = 0, best = 0;
for (int i = 0; i < (int)g[node].size(); i++)
{
int x = g[node][i];
if (x != father){
best = max(best, dfs(x, node));
prelist[node] += prelist[x];
best_child = max(best_child, prelist[x]);
}
}
prelist[node] = max(st, prelist[node] - st);
return max(best, max(prelist[node], best_child + st));
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n;
for (int i = 1; i < n; i++)
{
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
cin >> a;
cout << dfs(1, 0);
return 0;
}
