// oooo
/*
har chi delet mikhad bebar ~
gitar o ba khodet nabar! ~
;Amoo_Hasan;
*/
#include<bits/stdc++.h>
//#pragma GCC optimize("O3,no-stack-protector,unroll-loops")
//#pragma GCC target("avx2,fma")
using namespace std;
typedef long long ll;
typedef long double ld;
#define Sz(x) int((x).size())
#define All(x) (x).begin(), (x).end()
#define wtf(x) cout<<#x <<" : " <<x <<endl
constexpr ll inf = 1e18, N = 1e6 + 10, mod = 1e9 + 7, pr = 1000696969;
int dp[N][2];
bool mark[N];
string s;
vector<int> adj[N];
void dfs(int x, int p = 0) {
vector<int> cnt_0, cnt_1;
for(auto j : adj[x]) {
if(j == p) continue;
dfs(j, x);
cnt_0.push_back(dp[j][0]);
cnt_1.push_back(dp[j][1]);
}
sort(All(cnt_0), greater<int>());
sort(All(cnt_1), greater<int>());
if(mark[x]) {
dp[x][1] = 1;
int val = 0;
for(auto j : cnt_1) val += j;
dp[x][1] = max(dp[x][1], val - 1);
dp[x][0] = 1;
if(Sz(cnt_1) > 0) dp[x][0] = max(dp[x][0], 1 + cnt_1[0]);
if(Sz(cnt_0) > 0) dp[x][0] = max(dp[x][0], cnt_0[0]);
val = 0;
for(auto j : cnt_1) val += j;
dp[x][0] = max(dp[x][0], val - 1);
return;
}
int val = 0;
for(auto j : cnt_1) val += j;
dp[x][1] = val;
if(Sz(cnt_0) > 0) dp[x][0] = cnt_0[0];
val = 0;
for(auto j : cnt_1) val += j;
dp[x][0] = max(dp[x][0], val);
}
int main() {
ios :: sync_with_stdio(0), cin.tie(0);
int n; cin >>n;
for(int i = 0; i < n - 1; i++) {
int u, v; cin >>u >>v;
adj[u].push_back(v), adj[v].push_back(u);
}
cin >>s;
for(int i = 0; i < Sz(s); i++) mark[i + 1] = (s[i] == '1');
dfs(1);
cout<<dp[1][0];
return 0;
}
