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

#define rep(i,n) for(long long i=0;i<n;i++)
#define REP(i,s,n) for(long long i=(s);i<=(n);i++)
#define repr(i,n) for(long long i=n-1;i>=0;i--)
#define REPR(i,s,n) for(long long i=(s);i>=(n);i--)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define Eunique(v) v.erase(unique(all(v)),v.end())
#define Eback(s) s.erase(s.end()-1,s.end())
#define rev(v) reverse(all(v))
#define minvec(v) *min_element(all(v))
#define maxvec(v) *max_element(all(v))
#define sumvec(v) accumulate(all(v),0LL)
#define mapmin(v) v.rbegin()->first
#define mapmax(v) v.begin()->first
#define pb push_back
#define pf push_front
#define m_p make_pair
#define DOUBLE fixed << setprecision(15)
#define OK cerr<<"OK\n"
#define OK1 cerr<<"OK1\n"
#define OK2 cerr<<"OK2\n"
#define sz(s) (long long)s.size()
#define INF ((1LL<<62)-(1LL<<31))
#define zero(x,n) setw(x) << setfill('0') << n
#define endl '\n'

typedef long long ll;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<long long> vll;
typedef vector<vll> vvll;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<string> vs;

typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<pair<int,int>> vpii;
typedef vector<pair<ll,ll>> vpll;

const double pi = acos(-1.0);
const ll mod=1000000007;
//const ll mod=998244353;

template<class A, class B>
ostream& operator<<(ostream& ost, const pair<A, B>&p) {
	ost << "{" << p.first << ", " << p.second << "} ";
	return ost;
}

template<class T>
ostream& operator<<(ostream& ost, const vector<T>&v) {
	ost << "{";
	for (int i = 0; i<(int)v.size(); i++) {
		if (i)ost << " ";
		ost << v[i];
	}
	ost << "} \n";
	return ost;
}

template<class A, class B>
ostream& operator<<(ostream& ost, const map<A, B>&v) {
	ost << "{";
	for (auto p:v) {
		ost << "{" << p.first << ", " << p.second << "} ";
	}
	ost << "} ";
	return ost;
}

void out(){cout << "\n";}
template<class T,class... Args>
void out(const T &x,const Args &... args){
	cout << x << " ";
	out(args...);
}

template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
	for(T& e: vec) is >> e;
	return is;
}

template<typename T>
string join(vector<T>& vec, string sep=" "){
	stringstream ss;
	for(int i=0;i<(int)vec.size();i++){
		ss << vec[i] << (i+1==(int)vec.size()?"\n":sep);
	}
	return ss.str();
}

template<class T>
inline bool chmax(T& a, T b){if(a<b){a=b;return true;} return false;}

template<class T>
inline bool chmin(T& a, T b){if(a>b){a=b;return true;} return false;}

void YES(bool b) {cout << ((b)?"YES\n":"NO\n");}
void Yes(bool b) {cout << ((b)?"Yes\n":"No\n");}
void yes(bool b) {cout << ((b)?"yes\n":"no\n");}
void Yay(bool b) {cout << ((b)?"Yay!\n":":(\n");}

ll powmod(ll a,ll b){ll c=1; while(b>0){ if(b&1){ c=a*c%mod; } a=a*a%mod; b>>=1; } return c;}
ll invmod(ll a){ return powmod(a,mod-2); }
ll nCrmod(ll n,ll r){ll x=1,y=1; for(ll i=0;i<r;i++) {x=x*(n-i)%mod; y=y*(i+1)%mod; } return x*powmod(y,mod-2)%mod;}
ll gcd(ll x, ll y) {return __gcd(x,y);}
ll lcm(ll x, ll y) {return x/__gcd(x,y)*y;}

struct SCC{
	int V;
	vector<vector<int>> G, rG, T;
	vector<int> vs, used, cmp;
	SCC(){}
	SCC(int V) : V(V){ init(); }
	void init(){
		G.clear();
		rG.clear();
		vs.clear();
		used.clear();
		cmp.clear();
		T.clear();
		G.resize(V);
		rG.resize(V);
		used.resize(V);
		cmp.resize(V);
	}
	void add_edge(int from, int to){
		G[from].push_back(to);
		rG[to].push_back(from);
	}
	void dfs(int v){
		used[v] = 1;
		for(int i = 0; i < (int)G[v].size(); i++){
			if(!used[G[v][i]]) dfs(G[v][i]);
		}
		vs.push_back(v);
	}
	void rdfs(int v, int k){
		used[v] = 1;
		cmp[v] = k;
		T[k].push_back(v);
		for(int i = 0; i < (int)rG[v].size(); i++){
			if(!used[rG[v][i]]) rdfs(rG[v][i], k);
		}
	}
	int scc(){
		fill(used.begin(), used.end(), 0);
		vs.clear();
		for(int v = 0; v < V; v++){
			if(!used[v]) dfs(v);
		}
		fill(used.begin(), used.end(), 0);
		int k = 0;
		for(int i = (int)vs.size()-1; i >= 0; i--){
			if(!used[vs[i]]){
				T.push_back(vector<int>());
				rdfs(vs[i], k++);
			}
		}

		return k;
	}
};

int main()
{
	ll n, m;
	cin >> n >> m;
	SCC scc(n);
	rep(i,m){
		ll a, b;
		cin >> a >> b;
		scc.add_edge(a, b);
	}
	cout << (n != scc.scc()) << endl;
	return 0;
}



Measured memory_bytes: 3176