#include <bits/stdc++.h>
#define int long long
using namespace std;
int read()
{
    int x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9')
    {
        if (ch == '-')
            f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9')
    {
        x = (x << 1) + (x << 3) + (ch ^ 48);
        ch = getchar();
    }
    return x * f;
}
int n, m, u, v, pos, head[200001];
bool vis[100001];
struct edge
{
    int u, v, next;
} e[200001];
void add(int u, int v)
{
    e[++pos] = {u, v, head[u]};
    head[u] = pos;
}
vector<int> ans;
set<int> s[100001];
void dfs(int u, int fa = -1)
{
    for (int i = head[u]; i; i = e[i].next)
    {
        int v = e[i].v;
        if (v == fa)
            continue;
        dfs(v, u);
        if (s[u].size() > s[v].size())
        {
            for (auto x : s[v])
            {
                auto pos = s[u].find(x);
                if (pos != s[u].end())
                {
                    vis[u] = true;
                }
                else
                {
                    s[u].insert(x);
                }
            }
        }
        else
        {
            for (auto x : s[u])
            {
                auto pos = s[v].find(x);
                if (pos != s[v].end())
                {
                    vis[u] = 1;
                }
                else
                {
                    s[v].insert(x);
                }
            }
            swap(s[u], s[v]);
        }
    }
    if (vis[u])
    {
        ans.push_back(u);
        s[u].clear();
    }
}
signed main()
{
    n = read();
    for (int i = 1; i < n; i++)
    {
        u = read();
        v = read();
        add(u, v);
        add(v, u);
    }
    m = read();
    for (int i = 1; i <= m; i++)
    {
        u = read();
        v = read();
        if (u > v)
            swap(u, v);
        if (u == v)
        {
            vis[u] = true;
        }
        s[u].insert(i);
        s[v].insert(i);
    }
    dfs(1);
    printf("%lld\n", ans.size());
    sort(ans.begin(), ans.end());
    for (auto x : ans)
    {
        printf("%lld ", x);
    }
    return 0;
}