/*input
12 4
7 9
1 3
4 6
2 4
10 12
1 2
2 10
11 1
2 8
5 3
6 7
3
1
1
2
4
3
3
2
2
3
4
4
*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define int long long
#define double long double
#define f first
#define s second
#define mp make_pair
#define pb push_back
#define RE(i,n) for (int i = 1; i <= n; i++)
#define RED(i,n) for (int i = n; i > 0; i--)
#define REPS(i,n) for(int i = 1; (i*i) <= n; i++)
#define REP(i,n) for (int i = 0; i < (int)n; i++)
#define FOR(i,a,b) for (int i = a; i < b; i++)
#define REPD(i,n) for (int i = n-1; i >= 0; i--)
#define FORD(i,a,b) for (int i = a; i >= b; i--)
#define all(v) v.begin(),v.end()
#define pii pair<int,int>
#define vi vector<int>
#define vvi vector<vi>
#define print(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout << *it << " "; cout << endl;
#define debug(x) cout << x << endl;
#define debug2(x,y) cout << x << " " << y << endl;
#define debug3(x,y,z) cout << x << " " << y << " " << z << endl;
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
const int INF = 1e18+1;
const int MOD = 1e9+7;
const double PI = 3.14159265358979323846264338;
int raise(int a,int n,int m = MOD){
if(n == 0)return 1;
if(n == 1)return a;
int x = 1;
x *= raise(a,n/2,m);
x %= m;
x *= x;
x %= m;
if(n%2)x*= a;
x %= m;
return x;
}
int floor1(int n,int k){
if(n%k == 0 || n >= 0)return n/k;
return (n/k)-1;
}
int ceil1(int n,int k){
return floor1(n+k-1,k);
}
const int N = 2e5+1;
int n;
int k;
int col[N];
vector<int> all[N];
bool broken[N];
int freq[N];
int par[N];
set<int> adj[N];
int nn = 0;
int sub[N];
bool thisdone[N];
bool fine = 1;
int ans = INF;
int cur;
queue<int> q;
void dfs1(int u,int p){
nn++;
freq[col[u]]++;
sub[u] = 1;
for(int v:adj[u]){
if(v == p)continue;
dfs1(v,u);
sub[u] += sub[v];
}
}
void closecheck(int u,int p){
if(freq[col[u]] != all[col[u]].size())broken[col[u]] = 1;
par[u] = p;
for(int v:adj[u]){
if(v == p)continue;
closecheck(v,u);
}
}
void dellnow(int u,int p){
freq[col[u]]--;
thisdone[col[u]] = 0;
for(int v:adj[u]){
if(v == p)continue;
closecheck(v,u);
}
}
int findcen(int u,int p){
for(int v:adj[u]){
if(v == p)continue;
if(sub[v] > nn/2)return findcen(v,u);
}
return u;
}
void addcolor(int c){
if(broken[c]){fine = 0;return;}
if(thisdone[c])return;
thisdone[c] = 1;
cur++;
for(int v:all[c]){
q.push(v);
}
}
void cendfs(int u,int p = -1){
nn = 0;
dfs1(u,-1);
int centroid = findcen(u,-1);
// check here
closecheck(centroid,-1);
//cout << centroid << endl;
fine = 1;
cur = 0;
addcolor(col[centroid]);
while(!q.empty()){
int u= q.front();
q.pop();
if(par[u] != -1)addcolor(col[par[u]]);
}
//cout << fine << " " << cur << endl;
if(fine)ans = min(ans,cur);
//
dellnow(centroid,-1);
for(int u:adj[centroid]){
adj[u].erase(centroid);
cendfs(u,centroid);
}
}
void solve(){
cin >> n >> k;
RE(i,n-1){
int a,b;cin >> a >> b;
adj[a].insert(b);
adj[b].insert(a);
}
RE(i,n){
cin >> col[i];
all[col[i]].pb(i);
}
cendfs(1,-1);
cout << ans-1;
}
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//freopen(".in","r",stdin);freopen(".out","w",stdout);
int t = 1;
//cin >> t;
while(t--){
solve();
}
return 0;
}
