#include <cstdio>
#include <algorithm>
#include <vector>

const int Inf = 0x3f3f3f3f;
const int MN = 200005;

int N, a[MN];
std::vector<int> G[MN];

int par[MN], len[MN], gl[MN], b[MN];
void DFS0(int u, int p) {
	par[u] = p, b[u] = a[u];
	for (int v : G[u]) if (v != p) {
		DFS0(v, u);
		len[u] = std::max(len[u], len[v] + 1);
		b[u] += b[v];
	}
}
void DFS1(int u, int p) {
	static int seq[MN], pre[MN], suf[MN];
	int t = 0;
	for (int v : G[u]) if (v != p) seq[++t] = v;
	pre[0] = suf[t + 1] = gl[u] + 1;
	for (int i = 1; i <= t; ++i) pre[i] = suf[i] = len[seq[i]] + 1;
	for (int i = 1; i <= t; ++i) pre[i] = std::max(pre[i], pre[i - 1]);
	for (int i = t; i >= 1; --i) suf[i] = std::max(suf[i], suf[i + 1]);
	for (int i = 1; i <= t; ++i) gl[seq[i]] = std::max(pre[i - 1], suf[i + 1]);
	for (int v : G[u]) if (v != p) DFS1(v, u);
}

int lower[MN], upper[MN];

int main() {
	scanf("%d", &N);
	for (int i = 1, x, y; i < N; ++i) {
		scanf("%d%d", &x, &y);
		G[x].push_back(y);
		G[y].push_back(x);
	}
	for (int i = 1; i <= N; ++i) scanf("%1d", &a[i]);
	DFS0(1, 0), gl[1] = -1, DFS1(1, 0);
	for (int i = 1; i <= N; ++i) {
		int x = gl[i], y = -1, z = b[1] - b[i] ? gl[i] : Inf;
		for (int v : G[i]) if (v != par[i]) {
			if (len[v] > y) y = len[v];
			if (y > x) std::swap(x, y);
			z = std::min(z, b[v] ? len[v] : Inf);
		}
		upper[i] = std::min(x, y + 2);
		if (!a[i]) lower[i] = z + 1;
	}
	long long Ans = 1;
	for (int i = 1; i <= N; ++i) Ans += std::max(upper[i] - lower[i] + 1, 0);
	printf("%lld\n", Ans);
	return 0;
}