#ifndef EVAL
#include"grader.cpp"
#endif
#include<bits/stdc++.h>
using namespace std;
vector<int>g[1000005];
bool on[1000005],vis[1000005];
int n,deg[1000005];
bool flag;
#define DEBUG(x) cout<<#x<<"="<<x<<"\n"
void go(int v,int p){
if(on[v])return;
//cycle_size++;
vis[v]=1;
for(int to:g[v])if(to!=p){
if(vis[to]){
flag=true;
continue;
}
go(to,v);
}
}
bool check(){
for(int i=0;i<n;i++)vis[i]=0;
for(int i=0;i<n;i++){
if(on[i])continue;
if(deg[i]>2)return false;
if(vis[i])continue;
flag=false;
go(i,i);
if(flag)return false;
}
return true;
}
void Init(int N){
n=N;
}
void Link(int x,int y){
g[x].push_back(y);
g[y].push_back(x);
deg[x]++;
deg[y]++;
}
int CountCritical(){
int cnt=0;
for(int i=0;i<n;i++){
on[i]=true;
for(int to:g[i])deg[i]--,deg[to]--;
cnt+=check();
for(int to:g[i])deg[i]++,deg[to]++;
on[i]=false;
}
return cnt;
}
/*
7 13
-1
1 2
-1
0 5
-1
2 0
-1
3 2
-1
3 5
-1
4 3
-1
*/
