ArticulationPointandBridge

#include<bits/stdc++.h>
using namespace std;


#define pb push_back
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define M 100007
#define INF 1e9
#define INFL 1e18
#define PI acos(-1)
#define mp make_pair
#define fast_in_out ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);



vector<int>adj[M];



int parent[M];
int low[M];
int d[M];
int visited[M];
bool isArticulationPoint[M];
int Time=0;
bool mark[M];
vector<pair<int,int> >ans;
void DFS(int u,int root)
{
    Time=Time+1;
    visited[u]=1;
    d[u]=low[u]=Time;
    int noOfChildren=0;
    for(int i=0;i<adj[u].size();i++)
    {
        int v=adj[u][i];
        if(v==parent[u])
            continue;

        if(visited[v])
        {
            low[u]=min(low[u],d[v]);
        }
        else
        {
          parent[u]=v;

        DFS(v,root);
        low[u]=min(low[u],low[v]);
        if(low[v]>=d[u] && u!=root)
        {
            isArticulationPoint[u]=true;
            ans.pb(mp(u,v));
        }
        noOfChildren=noOfChildren+1;
        }
    if(u==root && noOfChildren>1)
    {
        isArticulationPoint[u]=true;
        ans.pb(mp(u,adj[u][0]));
    }
    }
}





int main()
{
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        int x,y;
        cin>>x>>y;
        adj[x].pb(y);
        adj[y].pb(x);
    }
    DFS(1,1);
    for(int i=1;i<=n;i++)
    {
        if(isArticulationPoint[i])
            cout<<i<<endl;
        //cout<<ans[i].first<<" "<<ans[i].second<<endl;
    }

    return 0;
}
//7
//1 2
//1 3
//3 4
//3 7
//4 5
//4 6
//6 7
//