void dfs(str& s, int u) {
vis[u] = true;
for (auto child: v[u]) if (!vis[child]) {
str* cs = new(str);
dfs(*cs, child);
merge(s, *cs);
delete(cs);
}
s.insert(c[u], 1);
for (auto query: q[u]) {
int pos = query.second, k = query.first;
result[pos] = s.query(k);
}
}
