#include <algorithm>
#include <iostream>
#include <numeric>
#include <cstring>
#include <iomanip>
#include <vector>
#include <bitset>
#include <stack>
#include <queue>
#include <cmath>
#include <set>
#include <map>
#define endl '\n'
#define X first
#define Y second
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
const int maxn = 2e5+10;
vector<int> G[maxn];
int dp[maxn][2];
string s;
void dfs(int v, int p)
{
int a = 0;
int b = 0;
int c = 0;
int k = 0;
for(int u: G[v])
{
if(u == p) continue;
dfs(u, v);
a += dp[u][1];
b = max(b, dp[u][0]);
c = max(c, dp[u][1]);
k++;
}
if(k == 0)
{
dp[v][0] = dp[v][1] = (s[v]-'0');
}
else if(k == 1)
{
if(s[v] == '1')
{
dp[v][0] = max(c+1, b);
dp[v][1] = max(1, a-1);
}
else
{
dp[v][0] = b;
dp[v][1] = c;
}
}
else
{
if(s[v] == '1')
{
dp[v][0] = max( max(1, a-1), max(c+1, b) );
dp[v][1] = max(1, a-1);
}
else
{
dp[v][0] = max(a, b);
dp[v][1] = a;
}
}
}
int32_t main()
{
ios::sync_with_stdio(false);
cin.tie(0);
int n; cin >> n;
for(int i = 1; i < n; i++)
{
int x, y; cin >> x >> y;
x--; y--;
G[x].push_back(y);
G[y].push_back(x);
}
cin >> s;
dfs(0, 0);
cout << dp[0][0] << endl;
return 0;
}
