node dfs(int u) {
node res(1,a[u]);
e[u] = true;
for (edge i = g.getHead(u); i; i = i->next) {
int v = i->to;
if (e[v]) continue;
node tmp = dfs(v);
res.first += tmp.first;
res.second += tmp.second;
}
return res;
}
void bfs() {
queue<int> q;
rep(i, 1, n+1) if (d[i] <= 1) q.push(i);
while (!q.empty()) {
int u = q.front(); q.pop();
if (e[u]) continue; e[u] = true;
if (d[u] != 1) continue;
for (edge i = g.getHead(u); i; i = i->next) {
int v = i->to;
if (e[v]) continue;
if ((--d[v]) == 1) q.push(v);
}
}
}
