// Problem: C. 覆盖
// Contest: undefined - NOIP2024训练赛 03
// URL: http://noi.ac/contest/1155/problem/2769
// Memory Limit: 1024 MB
// Time Limit: 1000 ms
// Challenger: Erica N
// ----
// 
#include<bits/stdc++.h>

using namespace std;
#define rd read()
#define ull unsigned long long
// #define int long long 
#define pb push_back
#define itn int
#define ps second 
#define pf first


#define rd read()
int read(){
  int xx = 0, ff = 1;char ch = getchar();
  while (ch < '0' || ch > '9'){
    if (ch == '-')ff = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9')xx = xx * 10 + (ch - '0'), ch = getchar();
  return xx * ff;
}
#define zerol = 1
#ifdef zerol
#define cdbg(x...) do { cerr << #x << " -> "; err(x); } while (0)
void err() {cerr << endl;}
template<template<typename...> class T, typename t, typename... A>
void err(T<t> a, A... x) {
	for (auto v: a) cerr << v << ' ';err(x...);
}
template<typename T, typename... A>
void err(T a, A... x) {
	cerr << a << ' ';err(x...);
}
#else
#define dbg(...)
#endif
const int N=2e6+5;
const ull P=137;
const int INF=1e18+7;
/*

策略


*/	


vector<int> e[N];

void add(int a,int b){
	e[a].pb(b);
	e[b].pb(a);
}


bitset<N>used;
multiset<int> g[N];

void dfs(int x,int fa){
	for(auto v:e[x]){
		if(v==fa)continue;
		dfs(v,x);
		// cdbg(x,v,g[v].size());
		if(used[v]||used[x])continue;
		g[x].insert(g[v].begin(),g[v].end());
		// merge(g[v],g[x]);
		g[v].clear();
	}
	int f=0;
	// cdbg(x);
	for(auto it=g[x].begin();it!=g[x].end();){
		auto it2=it;it++;
		if(it==g[x].end()){
			
			// cdbg(*it);
			break;
		}
		// cdbg(*it2);
		if(*it==*it2){
			// cdbg(*it);
			f=1;break;
		}
	}
	
	if(f){
		// cdbg("used",x);
		g[x].clear();used[x]=1;
	}
		
	
}

signed main(){
	int n=rd;
	for(int i=1;i<n;i++){
		add(rd,rd);
	}
	
	int m=rd;	
	for(int i=1;i<=m;i++){
		int a=rd,b=rd;
		if(a==b){
			used[a]=1;
		}else{
			g[a].insert(i);
			g[b].insert(i);
		}
	}
	
	
	dfs(1,0);
	
	cout<<used.count()<<endl;
	
	for(int i=1;i<=n;i++){
		if(used[i])cout<<i<<' ';
	}
}