#include <bits/stdc++.h>
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
const ll ILL=2167167167167167167;
const int INF=2100000000;
#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,T b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,T b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
bool yneos(bool a,bool upp=0){if(a){cout<<(upp?"YES\n":"Yes\n");}else{cout<<(upp?"NO\n":"No\n");}return a;}
template<class T> void vec_out(vector<T> &p,int ty=0){
    if(ty==2){cout<<'{';for(int i=0;i<(int)p.size();i++){if(i){cout<<",";}cout<<'"'<<p[i]<<'"';}cout<<"}\n";}
    else{if(ty==1){cout<<p.size()<<"\n";}for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){T ans=T(0);for(auto &x:a) ans+=x;return ans;}
int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}
template<class T> bool inside(T l,T x,T r){return l<=x&&x<r;}


const int D = 18;

struct node{
    ll sum = 0;
    int depth = D - 1;
    array<int, 2> to = {-1, -1};
};

int f(int a,int d){
    return (a & (1 << d)) != 0;
}

vector<node> nodes;

struct binary{
    int root;
    int C = 0;
    binary(){
        root = nodes.size();
        node tmp;
        nodes.push_back(tmp);
    }
    void set(int a, ll v = 1){
        a -= C;
        int ind = root;
        nodes[ind].sum += v;
        while (nodes[ind].depth != -1){
            int b = f(a, nodes[ind].depth);
            if (nodes[ind].to[b] == -1){
                nodes[ind].to[b] = nodes.size();
                node tmp;
                tmp.depth = nodes[ind].depth - 1;
                nodes.push_back(tmp);
            }
            ind = nodes[ind].to[b];
            nodes[ind].sum += v;
        }
    }
    ll prod(int l, int r){
        ll res = 0;
        r -= C;
        auto calc = [&](auto self, int ind, int vall, int varr){
            if (ind == -1) return;
            if (l <= vall && varr <= r){
                res += nodes[ind].sum;
                return;
            }
            if (varr <= l || r <= vall) return;
            varr = vall + (varr - vall) / 2;
            for (int i = 0; i < 2; i++){
                self(self, nodes[ind].to[i], vall, varr);
                swap(vall, varr);
                varr += 2 * (vall - varr);
            }
        };
        calc(calc, root, 0, 1 << D);
        return res;
    }
    vector<pair<int, ll>> get_list(){
        vector<pair<int, ll>> res;
        auto f = [&](auto self, int ind, int val) -> void {
            if (ind == -1) return;
            if (nodes[ind].depth == -1){
                res.push_back({val + C, nodes[ind].sum});
                return;
            }
            for (int i = 0; i < 2; i++){
                self(self, nodes[ind].to[i], val + i * (1 << nodes[ind].depth));
            }
        };
        f(f, root, 0);
        return res;
    }
};


std::vector<std::vector<int>> tree_in(int N){
    std::vector<std::vector<int>> G(N);
    for(int i=0;i<N-1;i++){
        int a;int b;
        cin>>a>>b;
        a--,b--;
        G[a].push_back(b);
        G[b].push_back(a);
    }
    return G;
}
std::tuple<std::vector<int>,std::vector<int>,std::vector<int>> tree_order_pare_depth(std::vector<std::vector<int>> &G,int root){
    int n=G.size();
    std::vector<int> order={root},pare(n,-1),depth(n);
    pare[root]=-2;
    for(int i=0;i<n;i++){
        int a=order[i];
        for(auto x:G[a]){
            if(pare[x]==-1){
                pare[x]=a;
                depth[x]=depth[a]+1;
                order.push_back(x);
            }
        }
    }
    return {order,pare,depth};
}
std::vector<int> tree_diameter_path(std::vector<std::vector<int>> &G){
    int n=G.size();
    auto r=(std::get<0>(tree_order_pare_depth(G,0))).at(n-1);
    std::vector<int> order,pare,depth,ans;
    tie(order,pare,depth)=tree_order_pare_depth(G,r);
    int ind=order[n-1];
    while(ind!=-2){
        ans.push_back(ind);
        ind=pare[ind];
    }
    return ans;
}
void solve();
// CYAN / FREDERIC
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    rep(i, 0, t) solve();
}

void solve(){
    int N;
    cin >> N;
    auto G = tree_in(N);
    string S;
    cin >> S;
    auto [order, pare, depth] = tree_order_pare_depth(G, 0);
    rep(i, 1, N){
        rep(j, 0, G[i].size()) if (G[i][j] == pare[i]) swap(G[i][j], G[i].back());
        G[i].pop_back();
    }
    vector<int> wei(N, 1);
    rep(i, 0, N){
        int a = order[N - i - 1];
        if (a) wei[pare[a]] += wei[a];
    }
    rep(i, 0, N) sort(all(G[i]), [&](int l, int r){return wei[l] > wei[r];});
    ll ans = 0;
    auto dfs = [&](auto self, int var) -> binary {
        binary base;
        int val = (S[var] == '1' ? -1 : 1);
        if (G[var].empty()){
            // nop
        }
        else{
            base = self(self, G[var][0]);
            rep(i, 1, G[var].size()){
                binary tmp = self(self, G[var][i]);
                // merge
                auto lis = tmp.get_list();
                for (auto x : lis){
                    ans += x.second * base.prod(0, 2 * N - x.first - val);
                }
                for (auto x : lis){
                    base.set(x.first, x.second);
                }
            }
        }
        base.set(N);
        base.C += val;
        ans += base.prod(0, N);
        //cout << var << " " << nodes[base.root].sum << "\n";
        //cout << ans << "\n";
        return base;
    };
    auto tr = dfs(dfs, 0);
    cout << ans << "\n";
}