#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll MOD=1e9+7;
const ll MOD2=998244353;
const ll N=4e5+5;
const ll K=350;
const ld pi=acos(-1);
const ll INF=(1LL<<60);
#define SQ(i) ((i)*(i))
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()
ll n,x,y,h[N],dp[N],ans,col[N],sum;
vector<ll> v[N];
string s;
void DFS(ll nd,ll pa){
dp[nd]=0;
for(auto i:v[nd]){
if(i==pa)continue;
DFS(i,nd);
dp[nd]+=dp[i];
}
dp[nd]=max(dp[nd]-col[nd],col[nd]);
return ;
}
void move(ll rt,ll to){
dp[rt]=0;
for(auto i:v[rt]){
if(i==to)continue;
dp[rt]+=dp[i];
}
dp[rt]=max(dp[rt]-col[rt],col[rt]);
dp[to]=0;
for(auto i:v[to]){
dp[to]+=dp[i];
}
dp[to]=max(dp[to]-col[to],col[to]);
}
void reroot(ll nd,ll pa){
ans=max(ans,dp[nd]);
for(auto i:v[nd]){
if(i==pa)continue;
move(nd,i);
reroot(i,nd);
move(i,nd);
}
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n;
REP(i,n-1)cin>>x>>y,v[x].pb(y),v[y].pb(x);
cin>>s;
REP(i,n)if(s[i]=='1')col[i+1]=1,++sum;
if(sum>=2)ans=2;else ans=sum;
DFS(1,0);
reroot(1,0);
cout<<ans<<"\n";
return 0;
}
