#include <bits/stdc++.h>
using namespace std;
#define MAXN 200'000
#define MAXM 200'000
#define LOGMAXN 18 // ceil(log2(MAXN))
typedef pair<int, int> ii;
int N, M, depth[MAXN + 5], parent[MAXN + 5][LOGMAXN + 5], fenwick[MAXN + 5];
int subtree_start[MAXN + 5], subtree_end[MAXN + 5], preord_cntr;
int A[MAXM + 5], B[MAXM + 5], app_LCA[MAXM + 5], app_process[MAXM + 5];
bool is_chosen[MAXN + 5];
vector <int> adjlist[MAXN + 5], chosen;
int lsb(int x)
{
return x & (-x);
}
int fw_point_query(int x)
{
int v = 0;
for (; x > 0; x -= lsb(x))
{
v += fenwick[x];
}
return v;
}
void fw_range_update(int l, int r, int v)
{
for (; l <= N; l += lsb(l))
{
fenwick[l] += v;
}
for (r++; r <= N; r += lsb(r))
{
fenwick[r] -= v;
}
}
void dfs_precompute(int v, int u, int d)
{
depth[v] = d;
parent[v][0] = u;
subtree_start[v] = ++preord_cntr;
for (int b = 1; b <= LOGMAXN; b++)
{
parent[v][b] = parent[parent[v][b - 1]][b - 1];
}
for (int w : adjlist[v])
{
if (w == parent[v][0])
{
continue;
}
dfs_precompute(w, v, d + 1);
}
subtree_end[v] = preord_cntr;
}
int get_lca(int u, int v)
{
if (depth[u] < depth[v])
{
swap(u, v);
}
int depth_diff = depth[u] - depth[v];
for (int b = LOGMAXN; b >= 0; b--)
{
if ((1 << b) & depth_diff)
{
u = parent[u][b];
}
}
if (u == v)
{
return u;
}
for (int b = LOGMAXN; b >= 0; b--)
{
if (parent[u][b] != parent[v][b])
{
u = parent[u][b];
v = parent[v][b];
}
}
assert(parent[u][0] == parent[v][0]);
return parent[u][0];
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> N >> M;
for (int i = 1; i <= N - 1; i++)
{
int u, v;
cin >> u >> v;
adjlist[u].push_back(v);
adjlist[v].push_back(u);
}
for (int j = 1; j <= M; j++)
{
cin >> A[j] >> B[j];
}
preord_cntr = 0;
dfs_precompute(1, 1, 1);
for (int j = 1; j <= M; j++)
{
app_LCA[j] = get_lca(A[j], B[j]);
app_process[j] = j;
}
sort(
app_process + 1, app_process + M + 1,
[](int l, int r)
{
if (depth[app_LCA[l]] == depth[app_LCA[r]])
{
return (l < r);
}
else
{
return (depth[app_LCA[l]] > depth[app_LCA[r]]);
}
}
);
for (int i = 1; i <= M; i++)
{
int j = app_process[i];
bool resolved = (
is_chosen[app_LCA[j]] ||
fw_point_query(subtree_start[A[j]]) > fw_point_query(subtree_start[app_LCA[j]]) ||
fw_point_query(subtree_start[B[j]]) > fw_point_query(subtree_start[app_LCA[j]])
);
if (!resolved)
{
is_chosen[app_LCA[j]] = true;
chosen.push_back(app_LCA[j]);
fw_range_update(subtree_start[app_LCA[j]], subtree_end[app_LCA[j]], 1);
}
}
cout << chosen.size() << "\n";
for (int i = 0; i < (int)chosen.size(); i++)
{
cout << chosen[i] << " \n"[i + 1 == (int)chosen.size()];
}
return 0;
}
