#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using vi = vector<int>;
using pi = pair <int, int>;
using vvi = vector<vi>;



void solve ()
{
    int n;
    cin >> n;
    vvi g(n);
    for (int i = 1; i < n; ++i)
    {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    int k;
    cin >> k;
    vi s1(k), s2(k);
    for (auto& x : s1)
        cin >> x;
    for (auto& x : s2)
        cin >> x;

    vi ins1(n), ins2(n);
    for (auto x : s1)
        ++ins1[x];
    for (auto x : s2)
        ++ins2[x];

    vi up(n), down(n);

    vector<tuple<int,int,int>> cmd, cmdback;

    auto Dfs = [&](auto&& self, int v, int f) -> int
    {
        int diff = ins1[v] - ins2[v];
        
        for (auto u : g[v])
        {
            if (u == f)
                continue;
            int c = self(self, u, v);
            diff += c;
            if (c > 0)
                cmd.emplace_back(u, v, c);
            if (c < 0)
                cmdback.emplace_back(v, u, -c);
        }
        return diff;
    };

    int r = Dfs(Dfs, 0, -1);
    if (r)
    {
        cout << "-1\n";
        return;
    }
    reverse(cmdback.begin(), cmdback.end());
    cout << (cmd.size() + cmdback.size()) << '\n';
    for (auto[f, t, c] : cmd)
        cout << f << ' ' << t << ' ' << c << '\n';
    for (auto[f, t, c] : cmdback)
        cout << f << ' ' << t << ' ' << c << '\n';
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    solve();
    return 0;
}