#include <bits/stdc++.h>
#define endl '\n'
#define debug(x) cout << #x << ": " << x << endl
using namespace std;
const int N = 2e5 + 5, LG = 20;
int n, m;
struct fenwick {
int bit[N];
void upd(int pos, int val) {
while (pos <= n) {
bit[pos] += val;
pos += pos & -pos;
}
}
int sum(int pos) {
int ret = 0;
while (pos >= 1) {
ret += bit[pos];
pos -= pos & -pos;
}
return ret;
}
void upd_range(int l, int r, int val) {
if (l > r) return;
upd(l, val);
if (r + 1 <= n) upd(r + 1, -val);
}
} fen;
vector<array<int, 3>> byDep[N];
vector<int> g[N];
int dep[N], tin[N], tout[N], tim, up[LG][N];
bool mark[N];
void dfs(int u, int p) {
tin[u] = ++tim;
up[0][u] = p;
for (int i = 1; i < LG; i++) up[i][u] = up[i - 1][up[i - 1][u]];
for (int v : g[u]) {
if (v == p) continue;
dep[v] = dep[u] + 1;
dfs(v, u);
}
tout[u] = tim;
}
bool is_anc(int u, int v) {
return tin[u] <= tin[v] && tout[v] <= tout[u];
}
int get_lca(int u, int v) {
if (is_anc(u, v)) return u;
if (is_anc(v, u)) return v;
for (int i = LG - 1; i >= 0; i--) {
if (up[i][u] != 0 && !is_anc(up[i][u], v)) u = up[i][u];
}
return up[0][u];
}
bool covered(int u, int v, int lca) {
int cnt = fen.sum(tin[u]) + fen.sum(tin[v]) - 2 * fen.sum(tin[lca]) + mark[lca];
return cnt > 0;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
dfs(1, 0);
for (int i = 1; i <= m; i++) {
int u, v;
cin >> u >> v;
int lca = get_lca(u, v);
byDep[dep[lca]].push_back({u, v, lca});
}
vector<int> ans;
for (int d = n; d >= 0; d--) {
for (auto [u, v, lca] : byDep[d]) {
if (covered(u, v, lca)) continue;
mark[lca] = 1;
ans.push_back(lca);
fen.upd_range(tin[lca], tout[lca], 1);
}
}
cout << ans.size() << endl;
for (int i : ans) cout << i << " ";
cout << endl;
return 0;
}
