#include <bits/stdc++.h>
using namespace std;
void dfs(int x, int p, vector<vector<int>> &AR, string &S, vector<int> &dp)
{
for (int i = 0; i < AR[x].size(); i++)
{
if (AR[x][i] == p)
continue;
dfs(AR[x][i], x, AR, S, dp);
dp[x] += dp[AR[x][i]];
}
if (S[x] == '1')
dp[x] = max(dp[x] - 1, 1);
}
void dfs2(int x, int p, vector<vector<int>> &AR, vector<int> &dp, string &S, int val)
{
dp[x] += val;
int sum = 0, best = 0;
for (int i = 0; i < AR[x].size(); i++)
{
if (AR[x][i] == p)
continue;
sum += dp[AR[x][i]];
best = max(best, dp[AR[x][i]]);
}
sum += val;
best = max(best, val);
if (S[x] == '1')
{
dp[x] = max(sum - 1, best + 1);
}
for (int i = 0; i < AR[x].size(); i++)
{
if (AR[x][i] == p)
continue;
int next = sum - dp[AR[x][i]];
if (S[x] == '1')
next = max(next - 1, 1);
dfs2(AR[x][i], x, AR, dp, S, next);
}
}
int main()
{
int N;
cin >> N;
vector<vector<int>> AR(N);
for (int i = 0; i < N - 1; i++)
{
int a, b;
cin >> a >> b;
a--, b--;
AR[a].push_back(b);
AR[b].push_back(a);
}
string S;
cin >> S;
vector<int> dp(N);
dfs(0, 0, AR, S, dp);
dfs2(0, 0, AR, dp, S, 0);
int best = 0;
for (int i = 0; i < N; i++)
best = max(best, dp[i]);
cout << best;
}
