#include<bits/stdc++.h> // https://blog.csdn.net/weixin_41100093/article/details/87857685
//菜到只会用原题了 
using namespace std;
const int maxn = 2e6+5;
int n, m;
set<int>Q[maxn];
vector<int>M[maxn];
vector<int>res;
int ans[maxn], tot = 0;
void dfs(int u, int fa){
    for(int i=0;i<M[u].size();++i){
        int v = M[u][i];
        if(v != fa){
            dfs(v, u);
            if(Q[u].size() < Q[v].size()) swap(Q[u], Q[v]);
            for(auto t : Q[v]){
                if(Q[u].find(t) != Q[u].end()){
                    ans[u] = 1;
                    break;
                }else{
                    Q[u].insert(t);
                }
            }
        }
    }
    if(ans[u] == 1){
        res.push_back(u);
        tot++; Q[u].clear();
    }
}
int main(){
    cin >> n;
    int u, v;
    for(int i=1;i<n;++i){
        scanf("%d %d", &u, &v);
        M[u].push_back(v);
        M[v].push_back(u);
    }
    cin >> m;
    for(int i=0;i<m;++i){
        scanf("%d %d", &u, &v);
        if(u == v){
            ans[u] = 1; continue;
        }
        Q[u].insert(i);
        Q[v].insert(i);
    }
    dfs(1, 0);
    cout << res.size() << endl;
    for(int i = res.size() - 1; i >= 0; i--){
        printf("%d ", res[i]);
    }
    return 0;
}