#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 100;
int dp[2][maxn];
vector <int> ne[maxn];
bool mark[maxn];
string str;
void dfs(int v)
{
if (str[v - 1] == '1')
{
dp[1][v] = dp[0][v] = 1;
}
mark[v] = 1;
int s = 0;
for (auto u : ne[v])
{
if (mark[u])
{
continue;
}
dfs(u);
s += dp[1][u];
dp[0][v] = max(dp[0][v], max(dp[0][u], dp[1][u] + (str[v - 1] == '1')));
}
dp[1][v] = max(dp[1][v], s - (str[v - 1] == '1'));
dp[0][v] = max(dp[0][v], s - (str[v - 1] == '1'));
return ;
}
int main()
{
int n;
cin >> n;
for (int i = 1;i < n;i++)
{
int v, u;
cin >> v >> u;
ne[v].push_back(u);
ne[u].push_back(v);
}
cin >> str;
dfs(1);
cout << dp[0][1];
}
