Problem: We have N boxes, numbered 1 through N. At first, box 1 contains one red ball, and each of the other boxes contains one white ball.

Snuke will perform the following M operations, one by one. In the i-th operation, he randomly picks one ball from box x_i, then he puts it into box y_i.

Find the number of boxes that may contain the red ball after all operations are performed.

Constraints

* 2≤N≤10^5
* 1≤M≤10^5
* 1≤x_i,y_i≤N
* x_i≠y_i
* Just before the i-th operation is performed, box x_i contains at least 1 ball.

Input

The input is given from Standard Input in the following format:


N M
x_1 y_1
:
x_M y_M


Output

Print the number of boxes that may contain the red ball after all operations are performed.

Examples

Input

3 2
1 2
2 3


Output

2


Input

3 3
1 2
2 3
2 3


Output

1


Input

4 4
1 2
2 3
4 1
3 4


Output

3

Solution (in JAVA):

Solution:
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.NoSuchElementException;

/*
                   _ooOoo_
                  o8888888o
                  88" . "88
                  (| -_- |)
                  O\  =  /O
               ____/`---'\____
             .'  \\|     |//  `.
            /  \\|||  :  |||//  \
           /  _||||| -:- |||||-  \
           |   | \\\  -  /// |   |
           | \_|  ''\---/''  |   |
           \  .-\__  `-`  ___/-. /
         ___`. .'  /--.--\  `. . __
      ."" '<  `.___\_<|>_/___.'  >'"".
     | | :  `- \`.;`\ _ /`;.`/ - ` : | |
     \  \ `-.   \_ __\ /__ _/   .-` /  /
======`-.____`-.___\_____/___.-`____.-'======
                   `=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            pass System Test!
*/

public class Main {
  private static class Task {
    void solve(FastScanner in, PrintWriter out) {
      int N = in.nextInt();
      int M = in.nextInt();
      boolean[] red = new boolean[N];
      red[0] = true;
      int[] cnt = new int[N];
      Arrays.fill(cnt, 1);
      for (int i = 0; i < M; i++) {
        int x = in.nextInt() - 1;
        int y = in.nextInt() - 1;
        cnt[x]--;
        cnt[y]++;
        if (red[x]) red[y] = true;
        if (cnt[x] == 0) red[x] = false;
      }

      int ans = 0;
      for (int i = 0; i < N; i++) {
        if (red[i]) ans++;
      }
      out.println(ans);
    }
  }

  class UnionFind {
    // par[i]：データiが属する木の親の番号。i == par[i]のとき、データiは木の根ノードである
    private int[] par;
    // sizes[i]：根ノードiの木に含まれるデータの数。iが根ノードでない場合は無意味な値となる
    private int[] sizes;

    // 木の数
    private int size;

    UnionFind(int n) {
      par = new int[n];
      sizes = new int[n];
      size = n;
      Arrays.fill(sizes, 1);
      // 最初は全てのデータiがグループiに存在するものとして初期化
      for (int i = 0; i < n; i++) par[i] = i;
    }

    /**
     * データxが属する木の根を得る
     *
     * @param x
     * @return
     */
    int find(int x) {
      if (x == par[x]) return x;
      return par[x] = find(par[x]);  // 根を張り替えながら再帰的に根ノードを探す
    }

    /**
     * 2つのデータx, yが属する木をマージする。
     * マージが必要なら true を返す
     *
     * @param x
     * @param y
     * @return
     */
    boolean unite(int x, int y) {
      // データの根ノードを得る
      x = find(x);
      y = find(y);

      // 既に同じ木に属しているならマージしない
      if (x == y) return false;

      // xの木がyの木より大きくなるようにする
      if (sizes[x] < sizes[y]) {
        int tx = x;
        x = y;
        y = tx;
      }

      // xがyの親になるように連結する
      par[y] = x;
      sizes[x] += sizes[y];
      sizes[y] = 0;  // sizes[y]は無意味な値となるので0を入れておいてもよい

      size--;
      return true;
    }

    /**
     * 2つのデータx, yが属する木が同じならtrueを返す
     *
     * @param x
     * @param y
     * @return
     */
    boolean isSame(int x, int y) {
      return find(x) == find(y);
    }

    /**
     * データxが含まれる木の大きさを返す
     *
     * @param x
     * @return
     */
    int partialSizeOf(int x) {
      return sizes[find(x)];
    }

    /**
     * 木の数を返す
     *
     * @return
     */
    int size() {
      return size;
    }
  }

  /**
   * ここから下はテンプレートです。
   */
  public static void main(String[] args) {
    OutputStream outputStream = System.out;
    FastScanner in = new FastScanner();
    PrintWriter out = new PrintWriter(outputStream);
    Task solver = new Task();
    solver.solve(in, out);
    out.close();
  }
  private static class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int bufferLength = 0;

    private boolean hasNextByte() {
      if (ptr < bufferLength) {
        return true;
      } else {
        ptr = 0;
        try {
          bufferLength = in.read(buffer);
        } catch (IOException e) {
          e.printStackTrace();
        }
        if (bufferLength <= 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;
    }

    private void skipUnprintable() {
      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    }

    boolean hasNext() {
      skipUnprintable();
      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();
    }

    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();
      }
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    double[] nextDoubleArray(int n) {
      double[] array = new double[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextDouble();
      }
      return array;
    }

    double[][] nextDoubleMap(int n, int m) {
      double[][] map = new double[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextDoubleArray(m);
      }
      return map;
    }

    public int nextInt() {
      return (int) nextLong();
    }

    public int[] nextIntArray(int n) {
      int[] array = new int[n];
      for (int i = 0; i < n; i++) array[i] = nextInt();
      return array;
    }

    public long[] nextLongArray(int n) {
      long[] array = new long[n];
      for (int i = 0; i < n; i++) array[i] = nextLong();
      return array;
    }

    public String[] nextStringArray(int n) {
      String[] array = new String[n];
      for (int i = 0; i < n; i++) array[i] = next();
      return array;
    }

    public char[][] nextCharMap(int n) {
      char[][] array = new char[n][];
      for (int i = 0; i < n; i++) array[i] = next().toCharArray();
      return array;
    }
  }
}