#include <bits/stdc++.h>
//#include <quadmath.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
//#define sz(x) (int)x.size()
//#define sqr(x) x*x
#pragma GCC optimize("-O3")
#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx,avx2,tune=native")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("fast-math")
using namespace std;
using namespace __gnu_pbds;
//#define int long long
//#define ld long double
template <class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long ll;
const int INF = 2e9;
vector<vector<int> > g;
vector<int> dep;
vector<bool> used;
vector<vector<int> > up;
vector<bool> deld;
vector<int> dist;
vector<int> sh;
int l = 0;
void calc(int v, int p, int d)
{
up[0][v] = p;
for (int i = 1; i < l; i++)
{
up[i][v] = up[i - 1][up[i - 1][v]];
}
dep[v] = d;
for (auto& u : g[v])
{
if (u != p)
{
calc(u, v, d + 1);
}
}
}
void del(int v, int p)
{
deld[v] = 1;
for (auto& u : g[v])
{
if (dist[u] < dist[v] && !deld[u] && u != p)
{
del(u, v);
}
}
}
void solve()
{
int n, k;
cin >> n >> k;
used.resize(n);
dist.resize(n, INF);
dep.resize(n);
g.resize(n);
deld.resize(n);
sh.resize(k);
for (int i = 0; i < n - 1; i++)
{
int x, y;
cin >> x >> y;
x--; y--;
g[x].push_back(y);
g[y].push_back(x);
}
while ((1 << l) <= n)
{
l++;
}
up.resize(l, vector<int>(n));
queue<int> q;
for (int i = 0; i < k; i++)
{
int x;
cin >> x;
x--;
sh[i] = x;
dist[x] = 0;
used[x] = 1;
q.push(x);
}
while (!q.empty())
{
int v = q.front();
q.pop();
for (auto& u : g[v])
{
if (dist[u] > dist[v] + 1)
{
dist[u] = dist[v] + 1;
q.push(u);
}
}
}
calc(0, 0, 0);
vector<int> ans;
sort(sh.begin(), sh.end(), [&](int i, int j) {return dep[i] > dep[j];});
for (int i = 0; i < k; i++)
{
if (deld[sh[i]]) continue;
int a = sh[i];
for (int j = l - 1; j >= 0; j--)
{
if (dist[up[j][a]] == dist[a] + (1 << j))
{
a = up[j][a];
}
}
ans.push_back(a);
del(a, a);
}
cout << ans.size() << endl;
for (auto& x : ans)
cout << x + 1 << ' ';
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t;
t = 1;
//cin >> t;
while (t--)
{
solve();
}
return 0;
}
/*
4 2 4
3 1 1 10
9 2 2 4
7 2 5 7;
4 1 8 10
5 3
5 6
5 9
1 10
*/
/*
4
1 3
2 4
2 3
3 4
*/
/*
1 1 1
100000000 1 1 1
1 1
*/
/*
????????????????????????????????????????????????
*/
