// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
// #define INTERACTIVE

#include <bits/stdc++.h>
using namespace std;

namespace templates {
// type
using ll  = long long;
using ull = unsigned long long;
using Pii = pair<int, int>;
using Pil = pair<int, ll>;
using Pli = pair<ll, int>;
using Pll = pair<ll, ll>;
template <class T>
using pq = priority_queue<T>;
template <class T>
using qp = priority_queue<T, vector<T>, greater<T>>;
// clang-format off
#define vec(T, A, ...) vector<T> A(__VA_ARGS__);
#define vvec(T, A, h, ...) vector<vector<T>> A(h, vector<T>(__VA_ARGS__));
#define vvvec(T, A, h1, h2, ...) vector<vector<vector<T>>> A(h1, vector<vector<T>>(h2, vector<T>(__VA_ARGS__)));
// clang-format on

// for loop
#define fori1(a) for (ll _ = 0; _ < (a); _++)
#define fori2(i, a) for (ll i = 0; i < (a); i++)
#define fori3(i, a, b) for (ll i = (a); i < (b); i++)
#define fori4(i, a, b, c) for (ll i = (a); ((c) > 0 || i > (b)) && ((c) < 0 || i < (b)); i += (c))
#define overload4(a, b, c, d, e, ...) e
#define fori(...) overload4(__VA_ARGS__, fori4, fori3, fori2, fori1)(__VA_ARGS__)

// declare and input
// clang-format off
#define INT(...) int __VA_ARGS__; inp(__VA_ARGS__);
#define LL(...) ll __VA_ARGS__; inp(__VA_ARGS__);
#define STRING(...) string __VA_ARGS__; inp(__VA_ARGS__);
#define CHAR(...) char __VA_ARGS__; inp(__VA_ARGS__);
#define DOUBLE(...) double __VA_ARGS__; STRING(str___); __VA_ARGS__ = stod(str___);
#define VEC(T, A, n) vector<T> A(n); inp(A);
#define VVEC(T, A, n, m) vector<vector<T>> A(n, vector<T>(m)); inp(A);
// clang-format on

// const value
const ll MOD1   = 1000000007;
const ll MOD9   = 998244353;
const double PI = acos(-1);

// other macro
#if !defined(RIN__LOCAL) && !defined(INTERACTIVE)
#define endl "\n"
#endif
#define spa ' '
#define len(A) ll(A.size())
#define all(A) begin(A), end(A)

// function
vector<char> stoc(string &S) {
    int n = S.size();
    vector<char> ret(n);
    for (int i = 0; i < n; i++) ret[i] = S[i];
    return ret;
}
string ctos(vector<char> &S) {
    int n      = S.size();
    string ret = "";
    for (int i = 0; i < n; i++) ret += S[i];
    return ret;
}

template <class T>
auto min(const T &a) {
    return *min_element(all(a));
}
template <class T>
auto max(const T &a) {
    return *max_element(all(a));
}
template <class T, class S>
auto clamp(T &a, const S &l, const S &r) {
    return (a > r ? r : a < l ? l : a);
}
template <class T, class S>
inline bool chmax(T &a, const S &b) {
    return (a < b ? a = b, 1 : 0);
}
template <class T, class S>
inline bool chmin(T &a, const S &b) {
    return (a > b ? a = b, 1 : 0);
}
template <class T, class S>
inline bool chclamp(T &a, const S &l, const S &r) {
    auto b = clamp(a, l, r);
    return (a != b ? a = b, 1 : 0);
}

template <typename T>
T sum(vector<T> &A) {
    T tot = 0;
    for (auto a : A) tot += a;
    return tot;
}

template <typename T>
vector<T> compression(vector<T> X) {
    sort(all(X));
    X.erase(unique(all(X)), X.end());
    return X;
}

// input and output
namespace io {
// __int128_t
std::ostream &operator<<(std::ostream &dest, __int128_t value) {
    std::ostream::sentry s(dest);
    if (s) {
        __uint128_t tmp = value < 0 ? -value : value;
        char buffer[128];
        char *d = std::end(buffer);
        do {
            --d;
            *d = "0123456789"[tmp % 10];
            tmp /= 10;
        } while (tmp != 0);
        if (value < 0) {
            --d;
            *d = '-';
        }
        int len = std::end(buffer) - d;
        if (dest.rdbuf()->sputn(d, len) != len) {
            dest.setstate(std::ios_base::badbit);
        }
    }
    return dest;
}

// vector<T>
template <typename T>
istream &operator>>(istream &is, vector<T> &A) {
    for (auto &a : A) is >> a;
    return is;
}
template <typename T>
ostream &operator<<(ostream &os, vector<T> &A) {
    for (size_t i = 0; i < A.size(); i++) {
        os << A[i];
        if (i != A.size() - 1) os << ' ';
    }
    return os;
}

// vector<vector<T>>
template <typename T>
istream &operator>>(istream &is, vector<vector<T>> &A) {
    for (auto &a : A) is >> a;
    return is;
}
template <typename T>
ostream &operator<<(ostream &os, vector<vector<T>> &A) {
    for (size_t i = 0; i < A.size(); i++) {
        os << A[i];
        if (i != A.size() - 1) os << endl;
    }
    return os;
}

// pair<S, T>
template <typename S, typename T>
istream &operator>>(istream &is, pair<S, T> &A) {
    is >> A.first >> A.second;
    return is;
}
template <typename S, typename T>
ostream &operator<<(ostream &os, pair<S, T> &A) {
    os << A.first << ' ' << A.second;
    return os;
}

// vector<pair<S, T>>
template <typename S, typename T>
istream &operator>>(istream &is, vector<pair<S, T>> &A) {
    for (size_t i = 0; i < A.size(); i++) {
        is >> A[i];
    }
    return is;
}
template <typename S, typename T>
ostream &operator<<(ostream &os, vector<pair<S, T>> &A) {
    for (size_t i = 0; i < A.size(); i++) {
        os << A[i];
        if (i != A.size() - 1) os << endl;
    }
    return os;
}

// tuple
template <typename T, size_t N>
struct TuplePrint {
    static ostream &print(ostream &os, const T &t) {
        TuplePrint<T, N - 1>::print(os, t);
        os << ' ' << get<N - 1>(t);
        return os;
    }
};
template <typename T>
struct TuplePrint<T, 1> {
    static ostream &print(ostream &os, const T &t) {
        os << get<0>(t);
        return os;
    }
};
template <typename... Args>
ostream &operator<<(ostream &os, const tuple<Args...> &t) {
    TuplePrint<decltype(t), sizeof...(Args)>::print(os, t);
    return os;
}

// io functions
void FLUSH() {
    cout << flush;
}

void print() {
    cout << endl;
}
template <class Head, class... Tail>
void print(Head &&head, Tail &&...tail) {
    cout << head;
    if (sizeof...(Tail)) cout << spa;
    print(std::forward<Tail>(tail)...);
}

template <typename T, typename S>
void prisep(vector<T> &A, S sep) {
    int n = A.size();
    for (int i = 0; i < n; i++) {
        cout << A[i];
        if (i != n - 1) cout << sep;
    }
    cout << endl;
}
template <typename T, typename S>
void priend(T A, S end) {
    cout << A << end;
}
template <typename T>
void prispa(T A) {
    priend(A, spa);
}
template <typename T, typename S>
bool printif(bool f, T A, S B) {
    if (f)
        print(A);
    else
        print(B);
    return f;
}

template <class... T>
void inp(T &...a) {
    (cin >> ... >> a);
}

} // namespace io
using namespace io;

// read graph
vector<vector<int>> read_edges(int n, int m, bool direct = false, int indexed = 1) {
    vector<vector<int>> edges(n, vector<int>());
    for (int i = 0; i < m; i++) {
        INT(u, v);
        u -= indexed;
        v -= indexed;
        edges[u].push_back(v);
        if (!direct) edges[v].push_back(u);
    }
    return edges;
}
vector<vector<int>> read_tree(int n, int indexed = 1) {
    return read_edges(n, n - 1, false, indexed);
}

template <typename T = long long>
vector<vector<pair<int, T>>> read_wedges(int n, int m, bool direct = false, int indexed = 1) {
    vector<vector<pair<int, T>>> edges(n, vector<pair<int, T>>());
    for (int i = 0; i < m; i++) {
        INT(u, v);
        T w;
        inp(w);
        u -= indexed;
        v -= indexed;
        edges[u].push_back({v, w});
        if (!direct) edges[v].push_back({u, w});
    }
    return edges;
}
template <typename T = long long>
vector<vector<pair<int, T>>> read_wtree(int n, int indexed = 1) {
    return read_wedges<T>(n, n - 1, false, indexed);
}

// yes / no
namespace yesno {

// yes
inline bool yes(bool f = true) {
    cout << (f ? "yes" : "no") << endl;
    return f;
}
inline bool Yes(bool f = true) {
    cout << (f ? "Yes" : "No") << endl;
    return f;
}
inline bool YES(bool f = true) {
    cout << (f ? "YES" : "NO") << endl;
    return f;
}

// no
inline bool no(bool f = true) {
    cout << (!f ? "yes" : "no") << endl;
    return f;
}
inline bool No(bool f = true) {
    cout << (!f ? "Yes" : "No") << endl;
    return f;
}
inline bool NO(bool f = true) {
    cout << (!f ? "YES" : "NO") << endl;
    return f;
}

// possible
inline bool possible(bool f = true) {
    cout << (f ? "possible" : "impossible") << endl;
    return f;
}
inline bool Possible(bool f = true) {
    cout << (f ? "Possible" : "Impossible") << endl;
    return f;
}
inline bool POSSIBLE(bool f = true) {
    cout << (f ? "POSSIBLE" : "IMPOSSIBLE") << endl;
    return f;
}

// impossible
inline bool impossible(bool f = true) {
    cout << (!f ? "possible" : "impossible") << endl;
    return f;
}
inline bool Impossible(bool f = true) {
    cout << (!f ? "Possible" : "Impossible") << endl;
    return f;
}
inline bool IMPOSSIBLE(bool f = true) {
    cout << (!f ? "POSSIBLE" : "IMPOSSIBLE") << endl;
    return f;
}

// Alice Bob
inline bool Alice(bool f = true) {
    cout << (f ? "Alice" : "Bob") << endl;
    return f;
}
inline bool Bob(bool f = true) {
    cout << (f ? "Bob" : "Alice") << endl;
    return f;
}

// Takahashi Aoki
inline bool Takahashi(bool f = true) {
    cout << (f ? "Takahashi" : "Aoki") << endl;
    return f;
}
inline bool Aoki(bool f = true) {
    cout << (f ? "Aoki" : "Takahashi") << endl;
    return f;
}

} // namespace yesno
using namespace yesno;

} // namespace templates
using namespace templates;

template <typename T>
struct BIT {
    int n;
    std::vector<T> tree;

    BIT(int n) : n(n) {
        tree.assign(n + 1, T(0));
    }
    BIT() = default;
    T _sum(int i) {
        i++;
        T res = T(0);
        while (i > 0) {
            res += tree[i];
            i -= i & -i;
        }
        return res;
    }

    T sum(int l, int r) {
        return _sum(r - 1) - _sum(l - 1);
    }

    T sum(int r) {
        return _sum(r - 1);
    }

    T get(int i) {
        return _sum(i) - _sum(i - 1);
    }

    void add(int i, T x) {
        i++;
        while (i <= n) {
            tree[i] += x;
            i += i & -i;
        }
    }

    int lower_bound(T x) {
        int pos  = 0;
        int plus = 1;
        while (plus * 2 <= n) plus *= 2;
        while (plus > 0) {
            if ((pos + plus <= n) && (tree[pos + plus] < x)) {
                x -= tree[pos + plus];
                pos += plus;
            }
            plus >>= 1;
        }
        return pos;
    }
};

struct CentroidDecomposition {
  public:
    int n;
    std::vector<int> par;      // 重心分解した木の直接の親
    std::vector<int> depth;    // 重心分解した木の深さ
    std::vector<int> size;     // 頂点iを重心とする木のサイズ
    std::vector<int> childcnt; // 頂点iの子の個数
    std::vector<std::vector<int>> pars; // pars[i][j] := 頂点iの先祖のうち，深さがjである頂点
    std::vector<std::vector<int>> edges;
    std::vector<std::vector<int>> centroids; // centroids[i] := 深さiの重心の一覧
    std::vector<std::vector<int>> treeind; // treeind[i][j] := 頂点jが深さiの重心の何番目の部分木か
    std::vector<std::vector<int>> cent_depth; // cent_depth[i][j] := 頂点jと深さiの重心からの距離

    CentroidDecomposition() = default;
    CentroidDecomposition(int n) : n(n) {
        edges.resize(n);
        pars.resize(n);
        childcnt.resize(n);
        par.assign(n, -1);
        depth.assign(n, -1);
        size.assign(n, -1);
    }

    void add_edge(int u, int v) {
        edges[u].push_back(v);
        edges[v].push_back(u);
    }

    void read_edges(int indexed = 1, int m = -1) {
        if (m == -1) m = n - 1;
        while (m--) {
            int u, v;
            std::cin >> u >> v;
            add_edge(u - indexed, v - indexed);
        }
    }

    void build() {
        dfs(0, -1);
    }

    std::pair<std::vector<std::vector<std::vector<int>>>, std::vector<std::vector<int>>>
    dist_freq() {
        std::vector<std::vector<std::vector<int>>> dist(n);
        std::vector<std::vector<int>> disttot(n);
        for (int i = 0; i < n; i++) {
            std::stack<std::pair<int, std::pair<int, int>>> st;
            disttot[i] = {1};
            dist[i].assign(childcnt[i], {0});
            st.push({0, {i, -1}});
            while (!st.empty()) {
                int d    = st.top().first + 1;
                int pos  = st.top().second.first;
                int bpos = st.top().second.second;
                st.pop();
                for (auto npos : edges[pos]) {
                    if (npos == bpos || depth[npos] < depth[i]) continue;
                    st.push({d, {npos, pos}});

                    if (int(disttot[i].size()) == d)
                        disttot[i].push_back(1);
                    else
                        disttot[i][d]++;

                    int j = treeind[depth[i]][npos];
                    if (int(dist[i][j].size()) == d)
                        dist[i][j].push_back(1);
                    else
                        dist[i][j][d]++;
                }
            }
        }
        return {dist, disttot};
    }

    std::pair<std::vector<std::vector<std::vector<long long>>>, std::vector<std::vector<long long>>>
    dist_freq_ll() {
        std::vector<std::vector<std::vector<long long>>> dist(n);
        std::vector<std::vector<long long>> disttot(n);
        for (int i = 0; i < n; i++) {
            std::stack<std::pair<int, std::pair<int, int>>> st;
            disttot[i] = {1};
            dist[i].assign(childcnt[i], {0});
            st.push({0, {i, -1}});
            while (!st.empty()) {
                int d    = st.top().first + 1;
                int pos  = st.top().second.first;
                int bpos = st.top().second.second;
                st.pop();
                for (auto npos : edges[pos]) {
                    if (npos == bpos || depth[npos] < depth[i]) continue;
                    st.push({d, {npos, pos}});

                    if (int(disttot[i].size()) == d)
                        disttot[i].push_back(1);
                    else
                        disttot[i][d]++;

                    int j = treeind[depth[i]][npos];
                    if (int(dist[i][j].size()) == d)
                        dist[i][j].push_back(1);
                    else
                        dist[i][j][d]++;
                }
            }
        }
        return {dist, disttot};
    }

    std::vector<std::tuple<int, int, int>> cent_ind_dist(int u) {
        std::vector<std::tuple<int, int, int>>
            ret; // uの親 + u の各重心の {頂点番号，何番目の部分木か，距離}
        ret.emplace_back(u, -1, 0);
        for (int d = int(pars[u].size()) - 1; d >= 0; d--) {
            ret.emplace_back(pars[u][d], treeind[d][u], cent_depth[d][u]);
        }
        return ret;
    };

  private:
    void dfs(int pos, int bpos, int d = 0, int c = -1) {
        std::stack<int> st;
        st.push(pos);
        std::stack<int> route;
        int sz = 0;
        if (int(treeind.size()) <= d) treeind.push_back(std::vector<int>(n, -1));
        if (int(cent_depth.size()) <= d) cent_depth.push_back(std::vector<int>(n, -1));
        if (d != 0) cent_depth[d - 1][pos] = 1;
        while (!st.empty()) {
            int pos = st.top();
            st.pop();
            if (bpos != -1) pars[pos].push_back(bpos);
            depth[pos] = -2;
            route.push(pos);
            sz++;
            if (d >= 1) treeind[d - 1][pos] = c;
            for (auto npos : edges[pos]) {
                if (depth[npos] == -1) {
                    st.push(npos);
                    if (d != 0) cent_depth[d - 1][npos] = cent_depth[d - 1][pos] + 1;
                }
            }
        }

        int g = -1;
        while (!route.empty()) {
            int pos = route.top();
            route.pop();
            size[pos]  = 1;
            depth[pos] = -1;
            bool isg   = true;
            for (auto npos : edges[pos]) {
                if (depth[npos] == -1) {
                    size[pos] += size[npos];
                    if (size[npos] * 2 > sz) isg = false;
                }
            }
            if (isg && 2 * size[pos] >= sz) {
                g = pos;
            }
        }

        if (int(centroids.size()) == d)
            centroids.push_back({g});
        else
            centroids[d].push_back(g);
        size[g]          = sz;
        par[g]           = bpos;
        depth[g]         = d;
        cent_depth[d][g] = 0;
        if (sz != 1) {
            int c = 0;
            for (auto npos : edges[g]) {
                if (depth[npos] == -1) dfs(npos, g, d + 1, c++);
            }
            childcnt[g] = c;
        }
    }
};

void solve() {
    INT(n);
    CentroidDecomposition G(n);
    G.read_edges();
    G.build();
    STRING(S);

    ll ans = 0;
    BIT<ll> bit(2 * n + 10);
    int zero = n + 5;
    fori(d, G.centroids.size()) {
        vec(ll, C, n, 0);
        vec(bool, used, n, false);
        for (auto c : G.centroids[d]) {
            used[c] = true;
            int mi  = 0;
            int ma  = 0;
            vec(int, inds, 0);
            inds.push_back(c);
            vec(int, ss, 0);
            C[c] = S[c] == '1' ? 1 : -1;
            for (auto sc : G.edges[c]) {
                if (G.depth[sc] < G.depth[c]) continue;
                ss.push_back(len(inds));
                stack<int> st;
                st.push(sc);
                used[sc] = true;
                C[sc]    = C[c] + (S[sc] == '1' ? 1 : -1);
                while (!st.empty()) {
                    int pos = st.top();
                    inds.push_back(pos);
                    st.pop();
                    for (auto npos : G.edges[pos]) {
                        if (!used[npos] and G.depth[npos] > G.depth[c]) {
                            st.push(npos);
                            C[npos] = C[pos] + (S[npos] == '1' ? 1 : -1);
                            chmin(mi, C[npos]);
                            chmax(ma, C[npos]);
                            used[npos] = true;
                        }
                    }
                }
            }
            ss.push_back(len(inds));

            for (auto i : inds) {
                bit.add(C[i] + zero, 1);
            }
            for (auto i : inds) {
                int d = S[c] == '1' ? -C[i] + 1 : -C[i] - 1;
                ans += bit.sum(d + zero + 1, 2 * n + 10);
            }
            for (auto i : inds) {
                bit.add(C[i] + zero, -1);
            }

            fori(i, 1, len(ss)) {
                int bi = ss[i - 1];
                int ni = ss[i];
                fori(j, bi, ni) {
                    bit.add(C[inds[j]] + zero, 1);
                }
                fori(j, bi, ni) {
                    int d = S[c] == '1' ? -C[inds[j]] + 1 : -C[inds[j]] - 1;
                    ans -= bit.sum(d + zero + 1, 2 * n + 10);
                }
                fori(j, bi, ni) {
                    bit.add(C[inds[j]] + zero, -1);
                }
            }
        }
    }
    for (auto s : S) {
        if (s == '1') ans++;
    }
    ans /= 2;
    print(ans);
}

int main() {
#ifndef INTERACTIVE
    std::cin.tie(0)->sync_with_stdio(0);
#endif
    // std::cout << std::fixed << std::setprecision(12);
    int t;
    t = 1;
    // std::cin >> t;
    while (t--) solve();
    return 0;
}

//
//
// // #pragma GCC target("avx2")
// // #pragma GCC optimize("O3")
// // #pragma GCC optimize("unroll-loops")
// // #define INTERACTIVE
//
// #include "kyopro-cpp/template.hpp"
//
// #include "data_structure/BIT.hpp"
// #include "tree/CentroidDecomposition.hpp"
//
// void solve() {
//     INT(n);
//     CentroidDecomposition G(n);
//     G.read_edges();
//     G.build();
//     STRING(S);
//
//     ll ans = 0;
//     BIT<ll> bit(2 * n + 10);
//     int zero = n + 5;
//     fori(d, G.centroids.size()) {
//         vec(ll, C, n, 0);
//         vec(bool, used, n, false);
//         for (auto c : G.centroids[d]) {
//             used[c] = true;
//             int mi  = 0;
//             int ma  = 0;
//             vec(int, inds, 0);
//             inds.push_back(c);
//             vec(int, ss, 0);
//             C[c] = S[c] == '1' ? 1 : -1;
//             for (auto sc : G.edges[c]) {
//                 if (G.depth[sc] < G.depth[c]) continue;
//                 ss.push_back(len(inds));
//                 stack<int> st;
//                 st.push(sc);
//                 used[sc] = true;
//                 C[sc]    = C[c] + (S[sc] == '1' ? 1 : -1);
//                 while (!st.empty()) {
//                     int pos = st.top();
//                     inds.push_back(pos);
//                     st.pop();
//                     for (auto npos : G.edges[pos]) {
//                         if (!used[npos] and G.depth[npos] > G.depth[c]) {
//                             st.push(npos);
//                             C[npos] = C[pos] + (S[npos] == '1' ? 1 : -1);
//                             chmin(mi, C[npos]);
//                             chmax(ma, C[npos]);
//                             used[npos] = true;
//                         }
//                     }
//                 }
//             }
//             ss.push_back(len(inds));
//
//             for (auto i : inds) {
//                 bit.add(C[i] + zero, 1);
//             }
//             for (auto i : inds) {
//                 int d = S[c] == '1' ? -C[i] + 1 : -C[i] - 1;
//                 ans += bit.sum(d + zero + 1, 2 * n + 10);
//             }
//             for (auto i : inds) {
//                 bit.add(C[i] + zero, -1);
//             }
//
//             fori(i, 1, len(ss)) {
//                 int bi = ss[i - 1];
//                 int ni = ss[i];
//                 fori(j, bi, ni) {
//                     bit.add(C[inds[j]] + zero, 1);
//                 }
//                 fori(j, bi, ni) {
//                     int d = S[c] == '1' ? -C[inds[j]] + 1 : -C[inds[j]] - 1;
//                     ans -= bit.sum(d + zero + 1, 2 * n + 10);
//                 }
//                 fori(j, bi, ni) {
//                     bit.add(C[inds[j]] + zero, -1);
//                 }
//             }
//         }
//     }
//     for (auto s : S) {
//         if (s == '1') ans++;
//     }
//     ans /= 2;
//     print(ans);
// }
//
// int main() {
// #ifndef INTERACTIVE
//     std::cin.tie(0)->sync_with_stdio(0);
// #endif
//     // std::cout << std::fixed << std::setprecision(12);
//     int t;
//     t = 1;
//     // std::cin >> t;
//     while (t--) solve();
//     return 0;
// }