#include <iostream>
#include <vector>
using namespace std;

int n;
vector<int> g[100000];
int par[100000][20];
int tin[100000];
int tout[100000];
bool used[100000];
int t = 0;

void dfs(int v, int p) {
	tin[v] = t++;
	par[v][0] = p;
	for (int i = 1; i < 20; i++) {
		par[v][i] = par[par[v][i - 1]][i - 1];
	}

	for (int to : g[v]) {
		if (to == p) continue;
		dfs(to, v);
	}
	tout[v] = t++;
}

bool upper(int v1, int v2) {
	if (v1 == -1) return 1;
	else if (v2 == -1) return 0;
	return tin[v1] <= tin[v2] && tout[v1] >= tout[v2];
}

int lca(int v1, int v2) {
	if (upper(v1, v2)) return v1;
	if (upper(v2, v1)) return v2;
	for (int i = 19; i >= 0; i--) {
		if (!upper(par[v1][i], v2)) v1 = par[v1][i];
	}
	return par[v1][0];
}

vector<int> ans;
vector<int> add[100000];
bool done[100000];
int l[100000];

vector<int> st;
int up = -1;

void dfs2(int v, int p) {
	for (int to : g[v]) {
		if (to == p) continue;
		dfs2(to, v);
	}

	for (int x : add[v]) {
		if (!used[x]) {
			st.push_back(x);
			if (up == 0) {
				up = l[x];
			} else {
				if (upper(up, l[x])) {
					up = l[x];
				}
			}
		}
	}
	if (v == up) {
		for (int x : st) {
			used[x] = 1;
		}
		up = -1;
		st.clear();
		ans.push_back(v);
	}
}

int main() {
	ios_base::sync_with_stdio(0);
	for (int i = 0; i < 100000; i++) {
		done[i] = 0;
	}
	cin >> n;
	for (int i = 1; i < n; i++) {
		int v, to;
		cin >> v >> to;
		v--;
		to--;
		g[v].push_back(to);
		g[to].push_back(v);
	}

	dfs(0, 0);
	int m;
	cin >> m;

	for (int i = 0; i < m; i++) {
		int v1, v2;
		cin >> v1 >> v2;
		v1--;
		v2--;
		int v = lca(v1, v2);
		add[v1].push_back(i);
		add[v2].push_back(i);
		l[i] = v;
	}

	dfs2(0, -1);

	cout << ans.size() << "\n";
	for (int x : ans) {
		cout << x + 1 << " ";
	}

	return 0;
}