#include <bits/stdc++.h>
#include <cassert>

using namespace std;

using ll = long long;
#define int long long
constexpr int N=2e5+10;
vector<int>g[N+1];
bool S1[N],S2[N];
int sz1[N], sz2[N];
int cnt[N];

vector<array<int, 3>> ops;

void dfs_sz(int v, int p=-1){
    sz1[v]=S1[v];
    sz2[v]=S2[v];
    cnt[v]=S1[v];
    for(int&u:g[v]){
        if(u==p)continue;
        dfs_sz(u, v);
        sz1[v]+=sz1[u];
        sz2[v]+=sz2[u];
    }
}

void dfs(int v, int p=-1){
    // cout<<v<<" "<<p<<endl;
    // assert(v!=p);
    vector<pair<int,int>>vec;
    for(int&u:g[v]){
        if(u==p)continue;
        // sz1[u] ? sz2[u]
        vec.push_back({(sz1[u]>=sz2[u]), u});
    }
    sort(vec.begin(), vec.end());
    reverse(vec.begin(), vec.end());
    for(auto&[_, u]:vec){
        // cout<<"!!! "<<v<<" "<<u<<" "<<sz1[u]<<" "<<sz2[u]<<" "<<cnt[v]<<endl;
        if(sz1[u]>=sz2[u]){
            dfs(u, v);
        }
        else{
            if(cnt[v]<sz2[u]-sz1[u]){
                // cout<<"! "<<v<<" "<<cnt[v]<<" "<<sz1[u]<<" "<<sz2[u]<<endl;
                cout<<-1<<endl;
                exit(0);
            }
            ops.push_back({v, u, sz2[u]-sz1[u]});
            cnt[v]-=sz2[u]-sz1[u];
            cnt[u]+=sz2[u]-sz1[u];
            dfs(u, v);
        }
    }
    if(S2[v]&&cnt[v]==0){
        // cout<<"! "<<v<<endl;
        cout<<-1<<endl;
        exit(0);
    }
    if(S2[v]){
        cnt[v]--;
    }
    if(cnt[v]>0&&p==-1){
        cout<<-1<<endl;
        exit(0);
    }
    if(cnt[v]>0){
        ops.push_back({v, p, cnt[v]});
        cnt[p]+=cnt[v];
    }
}

void solve(){
    int n;
    cin>>n;
    for(int i=1,x,y;i<n;i++){
        cin>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    int k;
    cin>>k;
    for(int i=0,x;i<k;i++){
        cin>>x;
        S1[x]=1;
    }
    for(int i=0,x;i<k;i++){
        cin>>x;
        S2[x]=1;
    }
    dfs_sz(0);
    dfs(0);
    assert((int)ops.size()<=10*n);
    cout<<endl;
    cout<<(int)ops.size()<<endl;
    for(auto&[v, u, l]:ops){
        cout<<v<<" "<<u<<" "<<l<<endl;
    }

}

int32_t main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int t=1;
    // cin>>t;
    for(int _=1;_<=t;_++){
        solve();
    }
}