public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int boxes = sc . nextInt ( ) ;
  int operations = sc . nextInt ( ) ;
  boolean [ ] redPossible = new boolean [ boxes + 1 ] ;
  redPossible [ 1 ] = true ;
  int [ ] boxBalls = new int [ boxes + 1 ] ;
  int possibility = 0 ;
  for ( int i = 1 ;
  i < boxBalls . length ;
  i ++ ) {
    boxBalls [ i ] = 1 ;
  }
  for ( int i = 0 ;
  i < operations ;
  i ++ ) {
    int pick = sc . nextInt ( ) ;
    int put = sc . nextInt ( ) ;
    if ( redPossible [ pick ] == true ) {
      redPossible [ put ] = true ;
    }
    boxBalls [ pick ] = boxBalls [ pick ] - 1 ;
    boxBalls [ put ] = boxBalls [ put ] + 1 ;
    if ( boxBalls [ pick ] == 0 ) {
      redPossible [ pick ] = false ;
    }
  }
  for ( int i = 0 ;
  i < redPossible . length ;
  i ++ ) {
    if ( redPossible [ i ] != false ) {
      possibility ++ ;
    }
  }
  System . out . println ( possibility ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int boxes = sc . nextInt ( ) ; int operations = sc . nextInt ( ) ; boolean [ ] redPossible = new boolean [ boxes + 1 ] ; redPossible [ 1 ] = true ; int [ ] boxBalls = new int [ boxes + 1 ] ; int possibility = 0 ; for ( int i = 1 ; i < boxBalls . length ; i ++ ) { boxBalls [ i ] = 1 ; } for ( int i = 0 ; i < operations ; i ++ ) { int pick = sc . nextInt ( ) ; int put = sc . nextInt ( ) ; if ( redPossible [ pick ] == true ) { redPossible [ put ] = true ; } boxBalls [ pick ] = boxBalls [ pick ] - 1 ; boxBalls [ put ] = boxBalls [ put ] + 1 ; if ( boxBalls [ pick ] == 0 ) { redPossible [ pick ] = false ; } } for ( int i = 0 ; i < redPossible . length ; i ++ ) { if ( redPossible [ i ] != false ) { possibility ++ ; } } System . out . println ( possibility ) ; }
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