#include <bits/stdc++.h>
using namespace std;
#define ll int
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;
#define f first
#define s second
#define lid(x) (x*2)
#define rid(x) (1+x*2)
typedef pair<ll, ll> pii;
typedef pair<pii, ll> piii;
const ll maxn = 5e5+55;
const ll max2 = 1e6+55;
const ll inf = 1e9;
const ll lg = 17;
const ll base = 101;
const ll modn = 998244353;
const ll mod2 = 1e9+9;
ll T, len, que, num, sum, x, fir, sec;
vector <ll> G[maxn];
ll dp[maxn][2];
string s;
void dfs(ll x, ll last) {
if(s[x-1] == '1') {
ll sigma = 0, max0 = 0, max1 = 0;
for(ll ver : G[x]) {
if(ver == last)
continue;
dfs(ver, x);
sigma += dp[ver][1], max0 = max(max0, dp[ver][0]), max1 = max(max1, dp[ver][1]);
}
dp[x][0] = max(1, max(sigma-1, max(max0, max1+1)));
dp[x][1] = max(1, sigma-1);
return;
}
ll sigma = 0, max0 = 0, max1 = 0;
for(ll ver : G[x]) {
if(ver == last)
continue;
dfs(ver, x);
sigma += dp[ver][1], max0 = max(max0, dp[ver][0]), max1 = max(max1, dp[ver][1]);
}
dp[x][0] = max(max0, sigma);
dp[x][1] = sigma;
}
int main()
{
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
cin >> len;
for(int i=1 ; i<len ; i++)
cin >> fir >> sec, G[fir].pb(sec), G[sec].pb(fir);
cin >> s;
dfs(1, 0);
cout << dp[1][0];
return 0;
}
