import java.io.IOException;
import java.io.InputStream;
import java.util.*;

public class Main {

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
         
        int v = sc.nextInt();
        int e = sc.nextInt();
        DGraph g = new DGraph(v);
        
        for(int i=0;i<e;i++){
        	g.addEdge(sc.nextInt(), sc.nextInt());
        }
        
        if(g.hasCycle()){
            System.out.println(1);
        }
        else{
            System.out.println(0);
        }
        
    }
	
}

class DGraph {

	NodeList[] nlist; //隣接リスト
	
	public DGraph(int vnum){
		this.nlist = new NodeList[vnum];
		for(int i=0;i<vnum;i++){
			nlist[i] = new NodeList();
		}
	}
	
	//辺の追加（同じ辺を複数回追加すると多重辺になる）
	void addEdge(int n, int m){
		nlist[n].add(m);
	}
	
	//頂点数を返す
	int vnum(){
		return nlist.length;
	}
	
	//辺数を返す
	int edgeNum(){
		int sum = 0;
		for(NodeList l:nlist){
			sum += l.size();
		}
		return sum;
	}
	
	//到達判定
	boolean isNext(int n, int m){
		return nlist[n].contains(m);
	}
	
	//1歩で到達可能な全ての頂点を返す
	NodeList nextList(int n){
		return nlist[n];
	}

	//トポロジカルソート（ans.size()!=vnum()ならDAGでなく、出力に意味はない））
	ArrayList<Integer> topologicalSort(){
		int idig[] = new int[vnum()]; //入次数
		for(int i=0;i<vnum();i++){
			for(int j:nextList(i)){
				idig[j] ++;
			}
		}
		ArrayDeque<Integer> q = new ArrayDeque<>();
		
		for(int i=0;i<vnum();i++){
			if(idig[i]==0){
				q.add(i); //入次数が0ならキューに入れる（DAGなら必ず存在）
			}
		}
		
		ArrayList<Integer> ans = new ArrayList<>();
		
		while(!q.isEmpty()){
			int now = q.pollFirst();
			ans.add(now);
			
			for(int j:nextList(now)){
				idig[j] --;
				if(idig[j]==0){
					q.add(j);
				}
			}
		}
		
		return ans;
	}
	
	//サイクルを持つか（DAGか）
	boolean hasCycle(){
		return !(topologicalSort().size() == vnum());
	}
	
	class NodeList extends ArrayList<Integer>{
		private static final long serialVersionUID = -4461479015945373120L;
	}
}

class FastScanner {
	private final InputStream in = System.in;
	private final byte[] buffer = new byte[1024];
	private int ptr = 0;
	private int buflen = 0;
	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		} else {
			ptr = 0;
			try {
				buflen = in.read(buffer);
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen <= 0) {
				return false;
			}
		}
		return true;
	}
	private int readByte() {
		if (hasNextByte())
			return buffer[ptr++];
		else
			return -1;
	}
	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}
	public boolean hasNext() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
		return hasNextByte();
	}
	public String next() {
		if (!hasNext())
			throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while (isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	public long nextLong() {
		if (!hasNext())
			throw new NoSuchElementException();
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while (true) {
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			} else if (b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			} else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}
	public int nextInt() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
			throw new NumberFormatException();
		return (int) nl;
	}
	public double nextDouble() {
		return Double.parseDouble(next());
	}
}


Measured memory_bytes: 24884