#include <bits/stdc++.h>
using namespace std;
const int NMAX = 200005;
vector<int> G[NMAX];
int values[NMAX];
int subtree[NMAX];
int h[NMAX], low[NMAX];
int total = 0;
int64_t ans = 1;
void dfs1(int node, int prev) {
  subtree[node] = 1;
  for (int to : G[node]) {
    if (to != prev) {
      dfs1(to, node);
      h[node] = max(h[node], h[to]);
      subtree[node] += subtree[to];
    }
  }
  ++h[node];
}
void dfs2(int node, int prev, int hup) {
  int hmax1 = hup, hmax2 = 0;
  int hnode = prev;
  int hmin = NMAX;
  for (int to : G[node]) {
    if (to != prev) {
      if (h[to] > hmax1) {
        hmax2 = hmax1;
        hmax1 = h[to];
        hnode = to;
      } else if (h[to] > hmax2) {
        hmax2 = h[to];
      }
      if (subtree[to] > 0) {
        hmin = min(hmin, h[to]);
      }
    }
  }
  hmax1++;
  hmax2++;
  int ch;
  if (hmax1 == hmax2) {
    ch = hmax2 - 1;
  } else {
    ch = hmax2;
    if (hmax1 > hmax2 + 1) {
      ch++;
    }
  }
  if (total - subtree[node] > 0) {
    hmin = min(hmin, hup);
  }
  hmin++;
  int vis = -1;
  if (values[node] != 1) {
    if (hmin == hmax1) {
      low[node] = hmax2 + 2;
      if (hnode == prev) {
        low[node] = max(low[node], low[hnode] + 2);
      } else {
        vis = hnode;
        dfs2(hnode, node, hmax2);
        low[node] = max(low[node], low[hnode] + 2);
      }
    } else {
      low[node] = hmin;
    }
  } else {
    low[node] = 1;
  }
  ans += max(ch - low[node] + 1, 0);
  for (int to : G[node]) {
    if (to != prev && to != vis) {
      if (h[to] == hmax1 - 1) {
        dfs2(to, node, hmax2);
      } else {
        dfs2(to, node, hmax1);
      }
    }
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  for (int i = 1; i < n; ++i) {
    int x, y;
    cin >> x >> y;
    x--;
    y--;
    G[x].push_back(y);
    G[y].push_back(x);
  }
  string s;
  cin >> s;
  for (int i = 0; i < n; ++i) {
    values[i] = s[i] - '0';
    total += values[i];
  }
  dfs1(0, -1);
  dfs2(0, -1, 0);
  cout << ans << '\n';
}
