```cpp // https://www.lanqiao.cn/problems/19704/learning/?page=1&first_category_id=1&name=%E5%9B%A2%E5%BB%BA #include <bits/stdc++.h> #define N 200020 using namespace std; typedef long long ll; ll n, m, ans = 0; vector<ll> t1v(N), t2v(N); // value[] map<ll, vector<ll>> tree1, tree2; // id, list[] void dfs(ll x, ll y, ll cnt) { if (t1v[x] != t2v[y]) return; ans = max(ans, cnt + 1); for (int i = 0; i < tree1[x].size(); i++) for (int j = 0; j < tree2[y].size(); j++) dfs(tree1[x][i], tree2[y][j], cnt + 1); } int main() { cin >> n >> m; for (int i = 1; i <= n; i++) cin >> t1v[i]; for (int i = 1; i <= m; i++) cin >> t2v[i]; for (int i = 1; i < n; i++) { ll u, v; cin >> u >> v; tree1[u].push_back(v); } for (int i = 1; i < m; i++) { ll p, q; cin >> p >> q; tree2[p].push_back(q); } dfs(1, 1, 0); cout << ans << endl; return 0; } ```