#include <cassert>// c
#include <iostream>// io
#include <iomanip>
#include <fstream>
#include <sstream>
#include <vector>// container
#include <map>
#include <set>
#include <queue>
#include <bitset>
#include <stack>
#include <algorithm>// other
#include <complex>
#include <numeric>
#include <functional>
using namespace std;

typedef int32_t i32;typedef int64_t i64;typedef i64 ll;typedef uint32_t uint;typedef uint64_t ull;

#define ALL(c) (begin(c)),(end(c))
#define REP(i,n) FOR(i,0,n)
#define REPr(i,n) FORr(i,0,n)
#define FOR(i,l,r) for(int i=(int)(l);i<(int)(r);++i)
#define FORr(i,l,r) for(int i=(int)(r)-1;i>=(int)(l);--i)
#define EACH(it,o) for(__typeof((o).begin()) it = (o).begin(); it != (o).end(); ++it)
#define IN(l,v,r) ((l)<=(v) && (v)<(r))

//debug
#define DUMP(x)  cerr << #x << " = " << (x)
#define DUMPLN(x)  DUMP(x) <<endl
#define DEBUG(x) DUMP(x) << LINE() << " " << __FILE__
#define DEBUGLN(x) DEBUG(x)<<endl
#define LINE()    cerr<< " (L" << __LINE__ << ")"
#define LINELN()    LINE()<<endl
#define CHECK(exp,act)  if(exp!=act){DUMPLN(exp);DEBUGLN(act);}
#define STOP(e)  CHECK(e,true);if(!(e)) exit(1);

class range {
private:
    struct Iter{
        int v;
        int operator*(){return v;}
        bool operator!=(Iter& itr) {return v < itr.v;}
        void operator++() {++v;}
    };
    Iter i, n;
public:
    range(int n) : i({0}), n({n}) {}
    range(int i, int n) : i({i}), n({n}) {}
    Iter& begin() {return i;}
    Iter& end() {return n;}
};

//output
template<typename T> ostream& operator << (ostream& os, const vector<T>& as){REP(i,as.size()){if(i!=0)os<<" "; os<<as[i];}return os;}
template<typename T> ostream& operator << (ostream& os, const vector<vector<T> >& as){REP(i,as.size()){if(i!=0)os<<endl; os<<as[i];}return os;}
template<typename T> ostream& operator << (ostream& os, const set<T>& ss){EACH(a,ss){if(a!=ss.begin())os<<" "; os<<a;}return os;}
template<typename T1,typename T2> ostream& operator << (ostream& os, const pair<T1,T2>& p){os<<p.first<<" "<<p.second;return os;}
template<typename K,typename V> ostream& operator << (ostream& os, const map<K,V>& m){bool isF=true;EACH(p,m){if(!isF)os<<endl;os<<p;isF=false;}return os;}

//input
char tmp[1000];
#define nextInt(n) scanf("%d",&n)
#define nextLong(n) scanf("%lld",&n) //I64d
#define nextDouble(n) scanf("%lf",&n) 
#define nextChar(n) scanf("%c",&n)
#define nextString(n) scanf("%s",tmp);n=tmp

// values
template<class T> T INF(){assert(false);};
template<> int INF<int>(){return 1<<28;};
template<> ll INF<ll>(){return 1LL<<58;};
template<> double INF<double>(){return 1e16;};


namespace Scc_kosaraju{
class Scc{
typedef vector<vector<int>> Graph;
private:
    int N;Graph g,rg;
    vector<int> vs;vector<bool> used;       
    void dfs(int v){
        used[v]=true;
        for(int to:g[v])if(!used[to])dfs(to);
        vs.push_back(v);
    }
    void rdfs(int v,int k){
        used[v]=true;cmp[v]=k;
        for(int to:rg[v])if(!used[to])rdfs(to,k);
    }
public:
    vector<int> cmp;//cmp...強連結成分を同一視したトポロジカルソート順序
    Scc(int N):N(N){
        g=rg=Graph(N);
        vs=cmp=vector<int>(N);used=vector<bool>(N);
    }
    void add_edge(int f,int t){
        g[f].push_back(t);rg[t].push_back(f);
    }
    int scc(){
        vs.clear();
        fill(ALL(used),false);
        REP(v,N)if(!used[v])dfs(v);
        fill(ALL(used),false);
        int k=0;REPr(v,N)if(!used[vs[v]])rdfs(vs[v],k++);
        return k;
    }
    bool same(int i,int j){return cmp[i]==cmp[j];}
    bool has_cycle(){
        //self loop
        REP(v,N)for(int to:g[v])if(to==v)return true;
        //cycle
        REP(i,N)REP(j,N)if(i!=j && same(i,j))return true;
        return false;
    }
};
}
using namespace Scc_kosaraju;

stringstream ss;
class Main{
    public:
    void run(){
        int n,m;cin >> n >> m;
        Scc g(n);
        REP(i,m){
            int s,t;cin >> s >> t;
            g.add_edge(s,t);
        }
        g.scc();
        cout << g.has_cycle() <<endl;
    }
};

int main(){
 cout <<fixed<<setprecision(20);
 cin.tie(0);
 ios::sync_with_stdio(false);
 Main().run();
 return 0;
}

Measured memory_bytes: 1256