// Black Radius
// * frank_c1
// * 2017 / 12 / 28

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

const int maxn = (int)(2e5) + 5;
const int INF = (int)(1e9);
vector<int> nxt[maxn];
char s[maxn];
int f[maxn], g[maxn];
int mi[maxn], mx[maxn];
multiset<int> h[maxn];
int su;

void _dfs(int x, int fa) {
	g[x] = (s[x] == '1');
	mi[x] = (s[x] == '1' ? 0 : INF);
	for (int i = 0; i < (int)nxt[x].size(); ++i)
		if (nxt[x][i] != fa) {
			_dfs(nxt[x][i], x);
			f[x] = max(f[x], f[nxt[x][i]] + 1);
			g[x] += g[nxt[x][i]];
			if (g[nxt[x][i]]) mi[x] = min(mi[x], f[nxt[x][i]] + 1);
			h[x].insert(f[nxt[x][i]]);
		}
}

void dfs(int x, int fa, int v) {
	mx[x] = min(max(v, f[x]) - 1, f[x] + 1);
	for (int i = 0; i < (int)nxt[x].size(); ++i)
		if (nxt[x][i] != fa) {
			h[x].erase(h[x].find(f[nxt[x][i]]));
			int c = max(v, (h[x].empty() ? -1 : *h[x].rbegin()) + 1) + 1;
			if (su - g[nxt[x][i]]) mi[nxt[x][i]] = min(mi[nxt[x][i]], c);
			dfs(nxt[x][i], x, c); mx[x] = min(mx[x], c);
			h[x].insert(f[nxt[x][i]]);
		}
}

int main() {
	int n;
	scanf("%d", &n);
	for (int i = 1; i < n; ++i) {
		int u, v; scanf("%d%d", &u, &v);
		nxt[u].push_back(v); nxt[v].push_back(u);
	} 
	scanf("%s", s + 1);
	for (int i = 1; i <= n; ++i) su += (s[i] == '1');
	_dfs(1, 0); dfs(1, 0, 0);
	LL ret = 0;
	for (int i = 1; i <= n; ++i) ret += max(mx[i] - mi[i] + 1, 0);
	return printf("%lld\n", ret + 1), 0;
}