public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int N = sc . nextInt ( ) ;
  int M = sc . nextInt ( ) ;
  int [ ] x = new int [ M ] ;
  int [ ] y = new int [ M ] ;
  for ( int i = 0 ;
  i < M ;
  i ++ ) {
    x [ i ] = sc . nextInt ( ) ;
    y [ i ] = sc . nextInt ( ) ;
  }
  boolean [ ] redExists = new boolean [ N + 1 ] ;
  int [ ] nums = new int [ N + 1 ] ;
  redExists [ 1 ] = true ;
  Arrays . fill ( nums , 1 ) ;
  for ( int i = 0 ;
  i < M ;
  i ++ ) {
    if ( redExists [ x [ i ] ] ) {
      if ( nums [ x [ i ] ] == 1 ) {
        redExists [ x [ i ] ] = false ;
      }
      redExists [ y [ i ] ] = true ;
    }
    nums [ x [ i ] ] -- ;
    nums [ y [ i ] ] ++ ;
  }
  int cnt = 0 ;
  for ( int n = 1 ;
  n <= N ;
  n ++ ) {
    if ( redExists [ n ] ) {
      cnt ++ ;
    }
  }
  out . println ( cnt ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int N = sc . nextInt ( ) ; int M = sc . nextInt ( ) ; int [ ] x = new int [ M ] ; int [ ] y = new int [ M ] ; for ( int i = 0 ; i < M ; i ++ ) { x [ i ] = sc . nextInt ( ) ; y [ i ] = sc . nextInt ( ) ; } boolean [ ] redExists = new boolean [ N + 1 ] ; int [ ] nums = new int [ N + 1 ] ; redExists [ 1 ] = true ; Arrays . fill ( nums , 1 ) ; for ( int i = 0 ; i < M ; i ++ ) { if ( redExists [ x [ i ] ] ) { if ( nums [ x [ i ] ] == 1 ) { redExists [ x [ i ] ] = false ; } redExists [ y [ i ] ] = true ; } nums [ x [ i ] ] -- ; nums [ y [ i ] ] ++ ; } int cnt = 0 ; for ( int n = 1 ; n <= N ; n ++ ) { if ( redExists [ n ] ) { cnt ++ ; } } out . println ( cnt ) ; }
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