#include <bits/stdc++.h>
#define fst first
#define snd second
#define pb push_back
#define mset(a,v) memset(a,v,sizeof(a))
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(),x.end()
#define forn(i,a,b) for(int i = a; i<b; i++)
#ifdef D
#define debug(x) cout << x
#else
#define debug(x) //nothing
#endif
using namespace std;
typedef long long ll;
const int MAXN = 2000+5;
ll n;
vector<ll> adj[MAXN];
bool is[MAXN];
ll down[MAXN][3];
ll pa[MAXN];
ll f(ll nd , ll t, ll p){
ll &res = down[nd][t];
if(res!=-1) return res;
pa[nd]=p;
if(is[nd]){
res=1;
}else res=0;
if(t==0){
ll pres = 0;
for(auto i:adj[nd]) if(i!=p){
pres+=f(i,0,nd);
}
res=max(res,pres- (is[nd]?1:0));
}else{
ll best = 0;
for(auto i:adj[nd]) if(i!=p){
best=max(best,f(i,0,nd));
}
res=max(res,best+(is[nd]?1:0));
}
debug("lastf "<<nd<<" "<<p<<" "<<res<<'\n');
return res;
}
ll up[MAXN][3];
ll dp[MAXN][3];
void newf(ll nd, ll t, ll p){
ll &res = dp[nd][t];
res=down[nd][0];
res=max(res,down[nd][1]);
up[nd][1]=(is[nd]?1:0);
up[nd][0]=-(is[nd]?1:0);
ll pres = up[p][0]; for(auto i:adj[p]) if(i!=nd && i!=pa[p]) up[nd][0]+=max(down[i][0],down[i][1]);
up[nd][0]=max(up[nd][0],pres-(is[nd]?1:0));
up[nd][0]=max(up[nd][0], up[p][1]-(is[nd]?1:0));
res=max(res, pres+(is[nd]?1:0));
res=max(res, up[p][1]+(is[nd]?1:0));
debug("newup "<<nd<<" "<<up[nd][0]);
debug("newf "<<nd<<" "<<res<<'\n');
for(auto i:adj[nd])if(i!=p){
newf(i,t,nd);
}
}
int main(){
cin>>n;
ll u,v;
forn(i,0,n-1){
cin>>u>>v; u--; v--;
adj[u].pb(v);
adj[v].pb(u);
}
string s; cin>>s;
forn(i,0,n) is[i]=(s[i]=='1');
ll res = 1;
mset(down,-1);
res=max(res,f(0,0,-1));
forn(i,0,n) res=max(res,f(i,1,pa[i]));
newf(0,1,-1);
forn(i,0,n){
res=max(res,dp[i][1]);
}
cout<<res<<'\n';
return 0;
}
