/*
_.-- ,.--.
.' .' /
@ |'..--------._
/ \._/ '.
/ .-.- \
( / \ \
\\ '. | #
\\ \ -. /
:\ | )._____.' \
" | / \ | \ )
| |./' :__ \.-'
'--'
*/
#include<bits/stdc++.h>
#define ll long long
#define llll pair<ll,ll>
#define ii pair<int,int>
#define fi first
#define se second
#define FOR(i,l,r) for(int i=l;i<=r;i++)
#define FOD(i,r,l) for(int i=r;i>=l;i--)
#define ull unsigned long long
#define iii pair<int,ii>
#define iv pair<pii,ii>
#define db double
#define ld long double
#define pb push_back
#define tdk "kfph"
using namespace std;
const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};
const int dxx[] = {1, 1, -1, -1, 2, 2, -2, -2};
const int dyy[] = {2, -2, 2, -2, 1, -1, 1, -1};
const ll INF=1e18;
const int N=2e5+5;
int dp[N],up[N],ans,su[N],pull[N],cnt[N];
vector<int> a[N];
int n;
string s;
void dfs(int u,int par)
{
dp[u]=(s[u]=='1');
int sum=-(s[u]=='1');
for(int v:a[u])
{
if(v==par) continue;
dfs(v,u);
ans=max(ans,(s[u]=='1')+dp[v]);
sum+=dp[v];
}
dp[u]=max(dp[u],sum);
ans=max(ans,dp[u]);
}
void kfph()
{
cin >> n;
for(int i=1;i<n;i++)
{
int u,v;
cin >> u >> v;
a[u].pb(v);
a[v].pb(u);
}
cin >> s;
s=' '+s;
dfs(1,-1);
cout << ans;
}
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
if(fopen(tdk".inp","r"))
{
freopen(tdk".inp","r",stdin);
freopen(tdk".out","w",stdout);
}
int t=1;
//cin >> t;
while(t--)
{
kfph();
}
return 0;
}
