/* made by amunduzbaev */
#include "bits/stdc++.h"
using namespace std;
//~ #include <ext/pb_ds/assoc_container.hpp>
//~ #include <ext/pb_ds/tree_policy.hpp>
//~ using namespace __gnu_pbds;
//~ template<class T> using oset = tree<T,
//~ null_type, less_equal<T>, rb_tree_tag,
//~ tree_order_statistics_node_update>;
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define ub upper_bound
#define lb lower_bound
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(),x.rend()
#define NeedForSpeed ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define vv vector
#define mem(arr, v) memset(arr, v, sizeof arr)
#define int long long
#define degub(x) cout<<#x<<" : "<<x<<"\n"
#define GG cout<<"here"<<endl;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vii;
typedef vector<pii> vpii;
template<class T> bool umin(T& a, const T& b) { return a > b ? a = b, true : false; }
template<class T> bool umax(T& a, const T& b) { return a < b ? a = b, true : false; }
template<int sz> using tut = array<int, sz>;
void usaco(string s) { freopen((s+".in").c_str(),"r",stdin);
freopen((s+".out").c_str(),"w",stdout); NeedForSpeed }
const int N = 2e5+5;
const int mod = 1e9+7;
const ll inf = 1e18;
const ld Pi = acos(-1);
#define MULTI 0
int n, m, k, s, t, q, ans, res, a[N];
int lca[N][20], tin[N], tout[N], llca[N];
int ns[N], d[N];
vii edges[N], qwe[N];
void predfs(int u, int p = -1){
tin[u] = t++;
for(int i=1;i<20;i++) lca[u][i] = lca[lca[u][i-1]][i-1];
for(auto x : qwe[u]){
if(x == p) continue;
lca[x][0] = u, d[x] = d[u] + 1;
if(a[x] == a[u]) ns[x] = ns[u];
else ns[x] = u;
predfs(x, u);
} tout[u] = t - 1;
}
bool par(int a, int b) { return (tin[a] <= tin[b] && tout[b] <= tout[a]); }
int LCA(int a, int b){
if(par(a, b)) return a;
if(par(b, a)) return b;
for(int i=19;i>=0;i--) if(!par(lca[a][i], b)) a = lca[a][i];
a = lca[a][0];
return a;
}
void dfs(int u, int p = -1){
if(d[ns[u]] >= d[llca[a[u]]] && ns[u]) edges[a[u]].pb(a[ns[u]]);
for(auto x : qwe[u]){
if(x == p) continue;
dfs(x, u);
}
}
int low[N], up[N], used[N], cmp[N], last, cost[N];
stack<int> ss;
vv<vii> tt;
void scc_dfs(int u){ used[u] = 1;
low[u] = up[u] = t++;
ss.push(u);
for(auto x : edges[u]){
if(used[x] && !cmp[x]) umin(low[u], up[x]);
else if(!used[x]) scc_dfs(x), umin(low[u], low[x]);
}
if(low[u] == up[u]){
int cur; ++last;
tt.pb({});
do{
cur = ss.top(); ss.pop();
tt.back().pb(cur);
cmp[cur] = last;
}while(cur != u);
cost[last] = sz(tt.back());
}
}
vii top;
void topsort(int u){ used[u] = 1;
for(auto x : qwe[u]){
if(!used[x]) topsort(x);
} top.pb(u);
}
void solve(int t_case){
cin>>n>>k;
for(int i=1;i<n;i++){
int a, b; cin>>a>>b;
qwe[a].pb(b), qwe[b].pb(a);
} for(int i=1;i<=n;i++) cin>>a[i];
predfs(1);
mem(llca, -1);
for(int i=1;i<=n;i++){
if(~llca[a[i]]) llca[a[i]] = LCA(llca[a[i]], i);
else llca[a[i]] = i;
} dfs(1);
for(int i=1;i<=k;i++){
set<int> ss;
for(auto x : edges[i]) ss.insert(x);
edges[i].clear();
for(auto x : ss) edges[i].pb(x);
//~ cout<<i<<" : ";
//~ for(auto x : edges[i]) cout<<x<<" ";
//~ cout<<endl;
}
//~ for(int i=1;i<=n;i++) cout<<ns[i]<<" ";
//~ cout<<endl;
t = 0;
/*
6 3
2 1
3 5
6 2
3 4
2 3
1 3 1 2 3 2
*/
for(int i=1;i<=k;i++){
if(used[i]) continue;
scc_dfs(i);
}
//~ GG
for(int i=1;i<=n;i++) qwe[i].clear();
for(auto xx : tt){
for(auto u : xx){
for(auto x : edges[u]){
qwe[cmp[u]].pb(cmp[x]);
}
}
}
//~ for(int i=1;i<=k;i++) cout<<cmp[i]<<" ";
//~ cout<<"\n";
//~ GG
n = last; mem(used, 0);
for(int i=1;i<=n;i++){
set<int> ss;
for(auto x : qwe[i]) ss.insert(x);
qwe[i].clear();
ss.erase(i);
for(auto x : ss) qwe[i].pb(x);
//~ cout<<i<<" : ";
//~ for(auto x : ss) cout<<x<<" ";
//~ cout<<"\n";
}
res = inf;
for(int i=1;i<=n;i++) if(!used[i]) topsort(i);
for(auto u : top){
for(auto x : qwe[u]) cost[u] += cost[x];
umin(res, cost[u]);
} cout<<res - 1<<"\n";
}
signed main(){
NeedForSpeed
if(MULTI){
int t; cin>>t;
for(int t_case = 1; t_case <= t; t_case++) solve(t_case);
} else solve(1);
return 0;
}
