Articulation Point

#include<stdio.h>
#include<string.h>
#include<vector>
#include<algorithm>
using namespace std;

#define MAX_V 107

vector<long> Edge[ MAX_V+7];
long nVertex;

bool Visit[ MAX_V+7];
long Ind[ MAX_V+7],I;// I for Ind countin
long nChild[ MAX_V+7];
bool IsArt[ MAX_V+7];
long Low[ MAX_V+7];
long p[ MAX_V+7];


void Dfs( long u)
{
    // init
    Visit[u] =true;
    Ind[u] =++I;
    nChild[u] =0;
    IsArt[u] =false;
    Low[u] =I;
    long i;
    for( i=0;i<Edge[u].size();i++){
        long v =Edge[u][i];
        if( !Visit[v]){
            p[v] =u;
            nChild[u]++;
            Dfs( v);
            // for findin bridge Low[v] > Ind[u]
            if( Low[v] >= Ind[u] && p[u]!=-1) IsArt[u] =true;
            Low[u] =min( Low[u],Low[v]);
        }
        else if( p[u] !=v){
            Low[u] =min( Low[u],Ind[v]);
        }
    }
}


long Calc( void)
{
    long i;
    memset( &Visit[1],0,sizeof(bool)*nVertex);
    for( i=1;i<=nVertex;i++){
        if( Visit[i]) continue;
        p[i] =-1;
        I =0;
        Dfs( i);
        if( nChild[i]>1) IsArt[i] =true;// special check for root
    };

    long Ans =0;
    for( i=1;i<=nVertex;i++){
        if( IsArt[i]) Ans++;
    }

    return Ans;
}


int main( void)
{
    Input();
    long Ans =Calc();
    printf("%ld\n",Ans);

    return 0;
}