#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#define ll long long
#define fori(i,j,k) for(ll i=j; i<=k;i++)
#define study ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define pb push_back
#define all(s) s.begin(),s.end()
#define ins insert
#define ss second
#define ff first
#ifndef DB
#define DB 0
#endif
#define debugl(l) if constexpr((l)<DB)
#define debug debugl(0)
const ll sz=2e5+10;
ll INF=1e12;
ll mod=1e9+7;
ll limit=1;
vector<vector<ll>>gr,s;
vector<ll>dist;
void restart(ll n,ll k){
gr.resize(n+10);
s.resize(n+10);
dist.assign(n+10,INF);
}
void work(){
ll n,k;
cin>>n>>k;
restart(n,k);
vector<ll>check(n+10,-1);
fori(i,1,n-1){
ll a,b;
cin>>a>>b;
gr[a].pb(b);
gr[b].pb(a);
}
queue<pair<ll,ll>>q;
fori(i,1,k){
ll nod;
cin>>nod;
q.push({0,nod});
dist[nod]=0;
s[nod].pb(nod);
check[nod]++;
}
while(!q.empty()){
ll nod=q.front().ss;
ll dit=q.front().ff;
q.pop();
if(dit!=dist[nod])
continue;
for(auto x: gr[nod]){
if((dit+1)<dist[x]){
dist[x]=dit+1;
s[x]=s[nod];
}
else if((dit+1)==dist[x]){
for(auto y: s[nod])
s[x].pb(y);
}
}
}
vector<pair<ll,ll>>yes;
fori(i,1,n){
yes.pb({s[i].size(),i});
}
vector<ll>ans(n+10,0);
ll cur=0;
sort(all(yes)); reverse(all(yes));
for(auto x: yes){
bool ok=1;
ll nod=x.ss;
for(auto y: s[nod]){
if(check[y]==0)
ok=0;
}
if(ok==1)
continue;
for(auto y: s[nod]){
check[y]++;
}
ans[nod]=1;
cur++;
}
for(auto x: yes){
ll nod=x.ss;
if(!ans[nod])
continue;
bool ok=0;
for(auto y: s[nod]){
if(check[y]==1)
ok=1;
}
if(ok) continue;
for(auto y: s[nod]){
check[y]--;
}
ans[nod]=0;
cur--;
}
cout<<cur<<endl;
fori(i,1,n){
if(ans[i])
cout<<i<<" ";
}
}
int main()
{
// #ifndef LOCAL
// freopen("snowcow.in","r",stdin);
// freopen("snowcow.out","w",stdout);
// #endif
study;
ll t=1;
//cin>>t;
fori(i,1,t){
work();
}
}
