#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define sd second
#define debug(x) cerr << #x << " -----> " << x << endl;
//#pragma GCC optimize("O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
const int mxN = 1e6 + 5;
ll n,a[mxN],val[mxN],in[mxN],out[mxN],t,k,val1[mxN],par[mxN][20];
vector<ll> vv,v[mxN];
bool vis[mxN];
void dfs(ll at){
for(int i = 1; i < 20; i++) par[at][i] = par[par[at][i - 1]][i - 1];
in[at] = t++;
for(auto it : v[at]){
if(it == par[at][0]) continue;
par[it][0] = at;
dfs(it);
}
out[at] = t;
}
bool check(ll at, ll it){
return (in[at] <= in[it] and out[at] >= out[it]);
}
ll lca(ll at, ll it){
if(check(at, it)) return at;
for(int i = 19; i >= 0; i--) if(!check(par[at][i], it)) at = par[at][i];
return par[at][0];
}
void dfs1(ll at){
for(auto it : v[at]){
if(it == par[at][0]) continue;
dfs1(it);
val[at] = lca(val[at], val[it]);
if(vis[it]) vis[at] = true;
}
if(val[at] == at and !vis[at]){
vis[at] = true;
vv.pb(at);
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n >> k;
for(int i = 0; i < n - 1; i++){
ll x,y;
cin >> x >> y;
v[x].pb(y);
v[y].pb(x);
}
for(int i = 1; i <= n; i++) cin >> a[i];
par[1][0] = 1;
dfs(1);
for(int i = 1; i <= n; i++){
if(val1[a[i]]) val1[a[i]] = lca(val1[a[i]], i);
else val1[a[i]] = i;
}
for(int i = 1; i <= n; i++) val[i] = val1[a[i]];
dfs1(1);
ll ans = vv.size(),x = vv[0];
if(ans == 1){
cout << 0;
return 0;
}
// debug(ans);
// debug(vv[0]);
for(int i = 1; i < vv.size(); i++) x = lca(x, vv[i]);
if(val[x] == 1) cout << (ans + 1) / 2;
else cout << ans / 2 + 1;
}
