#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 2e5 + 1;
const int MAX_K = 2e5 + 1;
bool isCentroid[MAX_N + 1], cityIn[MAX_N + 1];
int city[MAX_N + 1], sizee[MAX_N + 1], frecv[MAX_N + 1], frecvC[MAX_K + 1], parent[MAX_N + 1];
vector<int> adj[MAX_N + 1], towns[MAX_K + 1];
void calcSizes( int u, int p ) {
sizee[u] = 1;
for ( int v: adj[u] ) {
if ( v == p || isCentroid[v] )
continue;
calcSizes( v, u );
sizee[u] += sizee[v];
}
}
int centroid, sizetot;
void findCentroid( int u, int p ) {
int maxSize = sizetot - sizee[u];
for ( int v: adj[u] ) {
if ( v == p || isCentroid[v] )
continue;
findCentroid( v, u );
maxSize = max( maxSize, sizee[v] );
}
if ( maxSize <= sizetot / 2 )
centroid = u;
}
vector<int> vert;
void dfs( int u, int p ) {
parent[u] = p;
vert.push_back( u );
frecvC[city[u]]++;
for ( int v: adj[u] ) {
if ( v == p || isCentroid[v] )
continue;
dfs( v, u );
}
}
int minMerges;
void decomp( int r ) {
calcSizes( r, 0 );
sizetot = sizee[r];
findCentroid( r, 0 );
int c = centroid;
vert.clear();
dfs( c, 0 );
queue<int> q;
bool sePoate = true;
int m = 0;
if ( frecvC[city[c]] == frecv[city[c]] ) {
cityIn[city[c]] = true;
for ( int v: towns[city[c]] )
q.push( v );
while ( !q.empty() ) {
int v = q.front();
q.pop();
int x = city[parent[v]];
if ( x != 0 && !cityIn[x] ) {
cityIn[x] = true;
m++;
if ( frecvC[x] != frecv[x] ) {
sePoate = false;
break;
}
for ( int v: towns[x] )
q.push( v );
}
}
} else
sePoate = false;
if ( sePoate )
minMerges = min( minMerges, m );
for ( int v: vert ) {
frecvC[city[v]] = 0;
cityIn[city[v]] = false;
}
isCentroid[c] = true;
for ( int v: adj[c] ) {
if ( !isCentroid[v] )
decomp( v );
}
}
int main() {
int n, k;
cin >> n >> k;
for ( int i = 0; i < n - 1; i++ ) {
int u, v;
cin >> u >> v;
adj[u].push_back( v );
adj[v].push_back( u );
}
for ( int v = 1; v <= n; v++ ) {
cin >> city[v];
frecv[city[v]]++;
towns[city[v]].push_back( v );
}
minMerges = k - 1;
decomp( 1 );
cout << minMerges;
return 0;
}
