#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 50;
struct edge {
  int nxt, to;
} e[N << 1];
int fir[N], cnt = 0;
int n, Max[N], low[N], high[N];
char s[N];
inline void addedge(int x, int y) {
  e[++cnt] = (edge){fir[x], y};
  fir[x] = cnt;
}
inline void Dfs(int x, int fa) {
  for (int i = fir[x], y = e[i].to; i; i = e[i].nxt, y = e[i].to)
    if (y != fa) {
      Dfs(y, x);
      Max[x] = max(Max[x], Max[y] + 1);
    }
}
inline void Dfslow(int x, int fa, int lo) {}
inline void Dfshigh(int x, int fa, int lo) {
  int mx = ++lo, sb = 0;
  for (int i = fir[x], y = e[i].to; i; i = e[i].nxt, y = e[i].to)
    if (y != fa) {
      if (mx < Max[y] + 1) {
        sb = mx;
        mx = Max[y] + 1;
      } else
        sb = max(sb, Max[y] + 1);
    }
  high[x] = min(mx - 1, sb + 1);
  for (int i = fir[x], y = e[i].to; i; i = e[i].nxt, y = e[i].to)
    if (y != fa) Dfshigh(y, x, max(lo, Max[y] + 1 != mx ? mx : sb));
}
int main() {
  scanf("%d", &n);
  for (int i = 1, x, y; i < n; i++) {
    scanf("%d%d", &x, &y);
    addedge(x, y);
    addedge(y, x);
  }
  scanf("%s", s + 1);
  Dfs(1, 0);
  Dfshigh(1, 0, -1);
  long long ans = 1;
  for (int i = 1; i <= n; i++) ans += high[i] - low[i] + 1;
  printf("%lld\n", ans);
  return 0;
}
