// Copyright (C) 2017 __debug.

// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; version 3

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; If not, see <http://www.gnu.org/licenses/>.


#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/priority_queue.hpp>

#define x first
#define y second
#define MP std::make_pair
#define SZ(x) ((int)(x).size())
#define ALL(x) (x).begin(), (x).end()
#define DEBUG(...) fprintf(stderr, __VA_ARGS__)
#ifdef __linux__
#define getchar getchar_unlocked
#define putchar putchar_unlocked
#endif

using std::pair;
using std::vector;
using std::string;

typedef long long LL;
typedef pair<int, int> Pii;

const int oo = 0x3f3f3f3f;

template<typename T> inline bool chkmax(T &a, T b) { return a < b ? a = b, true : false; }
template<typename T> inline bool chkmin(T &a, T b) { return b < a ? a = b, true : false; }
string procStatus()
{
    std::ifstream t("/proc/self/status");
    return string(std::istreambuf_iterator<char>(t), std::istreambuf_iterator<char>());
}
template<typename T> T read(T &x)
{
    int f = 1;
    char ch = getchar();
    for (; !isdigit(ch); ch = getchar())
        f = (ch == '-' ? -1 : 1);
    for (x = 0; isdigit(ch); ch = getchar())
        x = 10 * x + ch - '0';
    return x *= f;
}
template<typename T> void write(T x)
{
    if (x == 0) {
        putchar('0');
        return;
    }
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    static char s[20];
    int top = 0;
    for (; x; x /= 10)
        s[++top] = x % 10 + '0';
    while (top)
        putchar(s[top--]);
}
// EOT

const int MAXN = 2e5 + 5;

int N;
vector<int> G[MAXN];
char S[MAXN];

void input()
{
    read(N);
    for (int i = 1; i < N; ++i) {
        int u, v;
        read(u); read(v);
        G[u].push_back(v);
        G[v].push_back(u);
    }
    scanf("%s", S + 1);
}

int maxd[MAXN], secd[MAXN], maxu[MAXN];
int costd[MAXN];
int cnt[MAXN];

void dfs1(int u, int f)
{
    costd[u] = (S[u] == '1' ? 0 : +oo);
    cnt[u] = (S[u] == '1');
    for (int i = 0; i < SZ(G[u]); ++i) {
        int v = G[u][i];
        if (v == f)
            continue;
        dfs1(v, u);
        if (chkmax(secd[u], maxd[v] + 1)) {
            if (secd[u] > maxd[u])
                std::swap(secd[u], maxd[u]);
        }
        if (cnt[v])
            chkmin(costd[u], maxd[v] + 1);
        cnt[u] += cnt[v];
    }
}

void dfs2(int u, int f, int x)
{
    maxu[u] = x;
    for (int i = 0; i < SZ(G[u]); ++i) {
        int v = G[u][i];
        if (v == f)
            continue;
        dfs2(v, u, std::max(x, (maxd[u] == maxd[v] + 1 ? secd[u] : maxd[u])) + 1);
    }
}

void solve()
{
    dfs1(1, 0);
    dfs2(1, 0, 0);

    LL ans = 1;

    for (int u = 1; u <= N; ++u) {
        if (chkmax(secd[u], maxu[u])) {
            if (secd[u] > maxd[u])
                std::swap(secd[u], maxd[u]);
        }
        LL rbnd = std::min(maxd[u] - 1, secd[u] + 1);
        LL lbnd = std::min(costd[u], cnt[u] == cnt[1] ? +oo : maxu[u]);
        if (lbnd <= rbnd)
            ans += rbnd - lbnd + 1;
    }

    printf("%lld\n", ans);
}

int main()
{
#ifdef __DEBUG
    freopen("F.in", "r", stdin);
    freopen("F.out", "w", stdout);
#endif

    input();
    solve();

    return 0;
}

// 弓满则折，月满则缺。


Measured memory_bytes: 29568