int cnt = 0;
vector<int> G[MAXN];
int pre[MAXN],low[MAXN];
void DFS(int u,int p)
{
    low[u] = pre[u] = ++cnt;
    for(auto v : G[u])
    {
    	if(!pre[v])
        {
            DFS(v,u);
            low[u] = min(low[u],low[v]);
        }
        else if(pre[v] < pre[u] && v != fa)
        {
            low[u] = min(low[u],pre[v]);
        }
    }
}

int cnt = 0;
vector<int> G[MAXN];
int pre[MAXN],low[MAXN],iscut[MAXN];
void DFS(int u,int p)
{
    low[u] = pre[u] = ++cnt;
    int child = 0;
    for(auto v : G[u])
    {
        if(!pre[v])
        {
            child ++;
            DFS(v,u);
            low[u] = min(low[u],low[v]);
            if(low[v] >= pre[u])
            {
              iscut[u] = 1;
            }
        }
        else if(pre[v] < pre[u] && v != p)
        {
            low[u] = min(low[u],pre[v]);
        }
    }
    if(p <= 0 && child == 1)
    {
        iscut[u] = 0;
    }
}

int cnt = 0;
vector<int> G[MAXN],isbridge[MAXN];
int pre[MAXN],low[MAXN],iscut[MAXN];
void DFS(int u,int p)
{
    low[u] = pre[u] = ++cnt;
    int child = 0;
    for(int i = 0;i < G[u].size();i++)
    {
    	int v = G[u][i];
        if(!pre[v])
        {
            child ++;
            DFS(v,u);
            low[u] = min(low[u],low[v]);
            if(low[v] > pre[u])
            {
              isbridge[u][i] = 1;
            }
        }
        else if(pre[v] < pre[u] && v != p)
        {
            low[u] = min(low[u],pre[v]);
        }
    }
}