#include <stdio.h>
#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <sstream>
#include <set>
#include <map>
#include <stack>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <string>
using namespace std;
#define ll long long
#define pi pair<int,int>
#define pll pair<ll,ll>
#define pii pair<int,pi>
#define X first
#define Y second
#define pb push_back
#define ab(x) ((x)<0?(-(x)):(x))
#define xx(x) ((x)*(x))
#define mp make_pair
#define vi vector<int>
#define vll vector<ll>
#define vs vector<string>
#define vpi vector<pi>
#define vpll vector<pll>
#define ALL(x) (x).begin(),(x).end()
#define Max (1<<30)
#define LLMax (1ll<<60)
template<class T>string ToString(T t){stringstream s;s<<t;return s.str();}
template<class T>void ToOther(T&t,string a){stringstream s(a);s>>t;}
int n,m;
vi v[100005];
int dep[100005];
int P[100005];
int cy[100005];
bool ck[100005];
void go(int x,int p,int D){
ck[x]=1;
dep[x]=D;
P[x]=p;
for(int i=0;i<v[x].size();i++){
int t=v[x][i];
if(t==p)continue;
if(ck[t])continue;
go(t,x,D+1);
}
}
void END(){cout<<"Not cactus"<<endl;exit(0);}
void calc(int a,int b){
int D=min(dep[a],dep[b]);
while(dep[a]>D){
if(++cy[a]==2)END();
a=P[a];
}
while(dep[b]>D){
if(++cy[b]==2)END();
b=P[b];
}
while(a!=b){
if(++cy[a]==2)END();
if(++cy[b]==2)END();
a=P[a];b=P[b];
}
if(++cy[a]==2)END();
}
void dfs(int x,int p){
ck[x]=1;
for(int i=0;i<v[x].size();i++){
int t=v[x][i];if(t==p)continue;
if(ck[t]){
if(t<x)calc(t,x);
continue;
}
dfs(t,x);
}
}
int main(){
scanf("%d%d",&n,&m);
for(int i=0;i<m;i++){
int s,e;scanf("%d%d",&s,&e);
v[s].pb(e);v[e].pb(s);
}
go(1,-1,0);
memset(ck,0,sizeof(ck));
dfs(1,-1);
cout<<"Cactus"<<endl;
}
