BB

#define AC (g[u][i])
void dfs(int u){
    cn[u]=1,h++,e[u]=d[u]=h;
    F((ll)g[u].size())
        if(!cn[AC])
            dfs(AC),D+=u==r,A[r]=D>=2,e[u]=min(e[u],e[AC]),A[u]|=e[AC]>=d[u]&&u!=r;
        else e[u]=min(e[u],d[AC]);
}
#define CLR F(n+1)g[i].clear(),e[i]=d[i]=cn[i]=A[i]=0;h=D=0;
#define CAL (dfs(r=1))