#include <iostream>
#include <vector>
using namespace std;
const int N = (1<<19);
vector<int> nei[N];
int Par[N][20], hei[N], c[N], ch[N], cnt[N], Mn[N], lca[N];
void dfs(int u, int p){
Par[u][0] = p;
hei[u] = hei[p] + 1;
for (int i=0;i<18;i++)
Par[u][i+1] = Par[Par[u][i]][i];
for (int i : nei[u]){
if (i != p)
dfs(i, u);
}
}
void dfs2(int u, int p){
for (int i : nei[u]){
if (i == p)
continue;
dfs2(i, u);
ch[u] += ch[i];
cnt[u] += cnt[i];
Mn[u] = min(Mn[u], Mn[i]);
}
if (Mn[u] == hei[u] and u - 1)
ch[u] = 1;
if (Mn[u] == hei[u] and cnt[u] == 0)
cnt[u] = 1;
}
int LCA(int u, int v){
if (hei[u] > hei[v])
swap(u, v);
for (int i=18;i>=0;i--){
if (hei[u] + (1<<i) <= hei[v])
v = Par[v][i];
}
for (int i=18;i>=0;i--){
if (Par[u][i] != Par[v][i])
u = Par[u][i], v = Par[v][i];
}
return (u == v ? u : Par[u][0]);
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int n, m;
cin>>n>>m;
for (int i=1;i<n;i++){
int a, b;
cin>>a>>b;
nei[a].push_back(b);
nei[b].push_back(a);
}
dfs(1, 0);
for (int i=1;i<=n;i++){
cin>>c[i];
if (lca[c[i]] == 0)
lca[c[i]] = i;
else
lca[c[i]] = LCA(lca[c[i]], i);
}
for (int i=1;i<=n;i++)
Mn[i] = hei[lca[c[i]]];
dfs2(1, 0);
if (ch[1] == 0)
cout<<0<<'\n';
else if (ch[1] == 1)
cout<<(cnt[1] + 2) / 2<<'\n';
else
cout<<(cnt[1] + 1) / 2<<'\n';
}
