#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
#define pb push_back
#define popb pop_back
#define all(x) (x).begin(), (x).end()
#define ff first
#define ss second
const int nax = 2e5 + 4;
int n;
string str;
int C[nax];
vi adj[nax];
int dp[nax][2][2];
int hw[nax], par[nax];
void dfs(int x, int p)
{
par[x] = p;
hw[x] = C[x];
for(auto e: adj[x])
{
if(e != p)
{
dfs(e,x );
hw[x] += hw[e];
}
}
}
int f(int x, int ext, int b)
{
if(dp[x][ext][b] != -1)
return dp[x][ext][b];
if(b && ext)
return dp[x][ext][b] = 1;
if(ext)
{
int rep = 0;
for(auto e: adj[x])
{
if(e != par[x] && hw[e] > 0 )
{
int p = C[e] ? f(e, 1, 1): 0;
int q = f(e, 1, 0);
rep += max(p, q);
}
}
return dp[x][ext][b] = max(0, rep - C[x]);
}
else
{
if(b)
{
int u= 0;
for(auto e: adj[x])
{
if(e != par[x] && hw[e] > 0)
{
int p = C[e] ? f(e, 1, 1): 0;
int q = f(e, 1, 0);
u = max(u, max(p, q));
}
}
return dp[x][ext][b] = u + 1;
}
else
{
int sum = 0;
int maxi = 0;
for(auto e: adj[x])
{
if(e != par[x] && hw[e] > 0 )
{
int p = C[e] ? f(e, 1, 1): 0;
int q= f(e, 1, 0);
int pp = C[e] ? f(e, 0, 1): 0 ;
int qp = f(e, 0, 0);
maxi = max(maxi, max(pp, qp));
sum += max(p, q);
}
}
return dp[x][ext][b] = max(maxi, sum - C[x]);
}
}
}
int32_t main()
{
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
memset(dp, -1,sizeof(dp));
cin >> n;
for(int i = 1; i < n;i ++)
{
int a, b;
cin >> a >> b;
adj[a].pb(b);
adj[b].pb(a);
}
cin >> str;
for(int i = 1; i <= n ;i ++)
C[i] = (str[i - 1] == '1');
dfs(1, 0);
int p = C[1] ? f(1, 0, 1): 0 ;
int q = f(1, 0, 0);
cout << max(p, q);
}
