public static void main ( String [ ] args ) {
  Scanner scan = new Scanner ( System . in ) ;
  N = scan . nextInt ( ) ;
  int M = scan . nextInt ( ) ;
  two = new int [ N ] ;
  two [ 0 ] = 1 ;
  for ( int i = 1 ;
  i < N ;
  i ++ ) {
    two [ i ] = two [ i - 1 ] * 2 ;
  }
  xy = new int [ N ] [ N ] ;
  for ( int i = 0 ;
  i < M ;
  i ++ ) {
    int x = scan . nextInt ( ) - 1 ;
    int y = scan . nextInt ( ) - 1 ;
    xy [ y ] [ x ] = - 1 ;
  }
  dp = new long [ two [ N - 1 ] * 2 ] ;
  dp [ 0 ] = 1 ;
  System . out . println ( res ( two [ N - 1 ] * 2 - 1 ) ) ;
}

public static void main ( String [ ] args ) { Scanner scan = new Scanner ( System . in ) ; N = scan . nextInt ( ) ; int M = scan . nextInt ( ) ; two = new int [ N ] ; two [ 0 ] = 1 ; for ( int i = 1 ; i < N ; i ++ ) { two [ i ] = two [ i - 1 ] * 2 ; } xy = new int [ N ] [ N ] ; for ( int i = 0 ; i < M ; i ++ ) { int x = scan . nextInt ( ) - 1 ; int y = scan . nextInt ( ) - 1 ; xy [ y ] [ x ] = - 1 ; } dp = new long [ two [ N - 1 ] * 2 ] ; dp [ 0 ] = 1 ; System . out . println ( res ( two [ N - 1 ] * 2 - 1 ) ) ; }
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