#include<bits/stdc++.h>

#define debug(x) cerr << #x << ": " << x << '\n'
#define debugArray(x,n) for(long long hoge = 0; (hoge) < (n); ++ (hoge)) cerr << #x << "[" << hoge << "]: " << x[hoge] << '\n'
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> vll;
const ll INF = LLONG_MAX/10;
const ll MOD = 1e9+7;

ll N;
string s;
vector<vll> G;
ll dist[200010];
bool fav[200010];
void dfs1(ll v,ll p){
  fav[v] = s[v]=='1';
  for(ll u:G[v])if(u!=p){
    dfs1(u,v);
    dist[v] = max(dist[v],dist[u]+1);
    fav[v] |= fav[u];
  }
}
ll ans;
void dfs2(ll v,ll p,ll d_p,bool f_p){
  //debug(v);
  vector<tuple<ll,ll> > dc;
  dc.emplace_back(0,-1);
  ll minfdc=INF;
  ll cntf=s[v]=='1';
  for(ll u:G[v]){
    if(u==p){
      dc.emplace_back(d_p+1,u);
      if(f_p){
        cntf++;
        minfdc = min(minfdc,d_p+1);
      }
    }else{
      dc.emplace_back(dist[u]+1,u);
      if(fav[u]){
        cntf++;
        minfdc = min(minfdc,dist[u]+1);
      }
    }
  }
  sort(dc.rbegin(),dc.rend());
  //debug(dc.size());
  if(dc.size()>=3){
    ans += max(0ll,(get<0>(dc[1]))+1-(s[v]=='1'? 0:minfdc));
  }else{
    ans += s[v]=='1';
  }
  if(p!=-1){
    if((d_p <= dist[v] && f_p)||(d_p >= dist[v]&&fav[v])){
      ans++;
    }
  }
  //debug(ans);
  for(ll u:G[v])if(u!=p){
    dfs2(u,v,get<0>(dc[get<1>(dc[0])==u]),(cntf>fav[u]));
  }
}
int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin>>N;
  G.resize(N);
  for(ll i=0;i<N-1;i++){
    ll a,b;cin>>a>>b;a--;b--;
    G[a].push_back(b);
    G[b].push_back(a);
  }
  cin>>s;
  dfs1(0,-1);
  dfs2(0,-1,0,false);
  cout<<ans<<endl;
  return 0;
}
