using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using SB = System.Text.StringBuilder;
//using System.Threading.Tasks;
//using System.Text.RegularExpressions;
//using System.Globalization;
//using System.Diagnostics;
using static System.Console;
using System.Numerics;
using static System.Math;
using pair = Pair<int, int>;

class Program
{
    static void Main()
    {
        SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().solve();
        Out.Flush();
    }
    readonly Scanner cin = new Scanner();
    readonly int[] dd = { 0, 1, 0, -1, 0 }; //→↓←↑
    readonly int mod = 1000000007;
    readonly int dom = 998244353;
    bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
    bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (b.CompareTo(a) < 0) { a = b; return true; } return false; }

    void solve()
    {
        int V = cin.nextint;
        int E = cin.nextint;
        var SCC = new StronglyConnectedComponents();
        int size = SCC.Run(SCC.Input(V, E, 0));

        if (size == V)
        {
            WriteLine("0");
        }
        else
        {
            WriteLine("1");
        }
    }

}

class StronglyConnectedComponents
{
    List<int>[] gg, rg;
    public List<int>[] dag;
    public int[] comp;
    bool[] used;
    public List<int> order;
    int[] size;
    int[] cont;

    public List<int>[] Input(int n, int m, int indexed = 1)
    {
        var cin = new Scanner();
        var G = new List<int>[n];
        for (int i = 0; i < G.Length; i++)
        {
            G[i] = new List<int>();
        }
        for (int i = 0; i < m; i++)
        {
            int a = cin.nextint - indexed;
            int b = cin.nextint - indexed;
            G[a].Add(b);
        }
        return G;
    }
    /// <summary>
    /// SCCして強連結成分数を返す。buildフラグで、dagに多重辺ありの縮約グラフを格納。
    /// </summary>
    /// <param name="G">隣接リスト</param>
    /// <returns>強連結成分の数</returns>
    public int Run(List<int>[] G, bool build = false)
    {
        // 準備
        int n = G.Length;
        comp = new int[n];
        used = new bool[n];
        order = new List<int>();
        gg = new List<int>[n];
        rg = new List<int>[n];
        for (int i = 0; i < n; i++)
        {
            gg[i] = new List<int>();
            rg[i] = new List<int>();
            comp[i] = -1;
        }
        for (int i = 0; i < n; i++)
        {
            foreach (var v in G[i])
            {
                gg[i].Add(v);
                rg[v].Add(i);
            }
        }

        // 実行
        for (int i = 0; i < n; i++)
        {
            dfs(i);
        }
        order.Reverse();
        int ptr = 0;
        foreach (var i in order)
        {
            if (comp[i] != -1) continue;
            rdfs(i, ptr);
            ptr++;
        }

        // データ整理
        cont = new int[ptr];
        size = new int[ptr];
        for (int i = 0; i < n; i++)
        {
            cont[comp[i]] = i;
            size[comp[i]]++;
        }
        if (build)
        {
            dag = new List<int>[ptr];
            for (int i = 0; i < dag.Length; i++)
            {
                dag[i] = new List<int>();
            }
            for (int i = 0; i < n; i++)
            {
                foreach (var to in G[i])
                {
                    int x = comp[i];
                    int y = comp[to];
                    if (x == y) continue;
                    dag[x].Add(y);
                }
            }
        }

        return ptr;
    }
    void dfs(int idx)
    {
        if (used[idx]) return;
        used[idx] = true;
        foreach (var to in gg[idx])
        {
            dfs(to);
        }
        order.Add(idx);
    }
    void rdfs(int idx, int cnt)
    {
        if (comp[idx] != -1) return;
        comp[idx] = cnt;
        foreach (var to in rg[idx])
        {
            rdfs(to, cnt);
        }
    }
    /// <summary>
    /// その頂点のトポロジカル順序の番号を返します
    /// </summary>
    /// <param name="id">頂点番号</param>
    /// <returns>トポロジカル順序の番号</returns>
    public int this[int id] => comp[id];
    /// <summary>
    /// トポロジカル順序がkである頂点の数
    /// </summary>
    /// <param name="k">トポロジカル順序の番号</param>
    /// <returns>頂点数</returns>
    public int Size(int k) => size[k];
    /// <summary>
    /// トポロジカル順序がkを代表する頂点
    /// </summary>
    /// <param name="k">トポロジカル順序の番号</param>
    /// <returns>頂点番号</returns>
    public int Cont(int k) => cont[k];
}

static class Ex
{
    public static void join<T>(this IEnumerable<T> values, string sep = " ") => WriteLine(string.Join(sep, values));
    public static string concat<T>(this IEnumerable<T> values) => string.Concat(values);
    public static string reverse(this string s) { var t = s.ToCharArray(); Array.Reverse(t); return t.concat(); }

    public static int lower_bound<T>(this IList<T> arr, T val) where T : IComparable<T>
    {
        int low = 0, high = arr.Count;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (arr[mid].CompareTo(val) < 0) low = mid + 1;
            else high = mid;
        }
        return low;
    }
    public static int upper_bound<T>(this IList<T> arr, T val) where T : IComparable<T>
    {
        int low = 0, high = arr.Count;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (arr[mid].CompareTo(val) <= 0) low = mid + 1;
            else high = mid;
        }
        return low;
    }
}

class Pair<T, U> : IComparable<Pair<T, U>> where T : IComparable<T> where U : IComparable<U>
{
    public T f; public U s;
    public Pair(T f, U s) { this.f = f; this.s = s; }
    public int CompareTo(Pair<T, U> a) => f.CompareTo(a.f) != 0 ? f.CompareTo(a.f) : s.CompareTo(a.s);
    public override string ToString() => $"{f} {s}";
}

class Scanner
{
    string[] s; int i;
    readonly char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] scan => ReadLine().Split();
    public int[] scanint => Array.ConvertAll(scan, int.Parse);
    public long[] scanlong => Array.ConvertAll(scan, long.Parse);
    public double[] scandouble => Array.ConvertAll(scan, double.Parse);
    public string next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next;
        }
    }
    public int nextint => int.Parse(next);
    public long nextlong => long.Parse(next);
    public double nextdouble => double.Parse(next);
}



Measured memory_bytes: 18040