public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int [ ] a = new int [ n ] ;
  int [ ] d = new int [ n ] ;
  int dmax = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    a [ i ] = sc . nextInt ( ) ;
    d [ a [ i ] ] ++ ;
    dmax = Math . max ( a [ i ] , dmax ) ;
  }
  if ( a [ 0 ] != 0 || d [ 0 ] != 1 ) {
    System . out . println ( 0 ) ;
    return ;
  }
  for ( int i = 0 ;
  i <= dmax ;
  i ++ ) {
    if ( d [ i ] == 0 ) {
      System . out . println ( 0 ) ;
      return ;
    }
  }
  long ans = 1L ;
  for ( int i = 1 ;
  i <= dmax ;
  i ++ ) {
    long tmp = pow ( 2 , d [ i - 1 ] ) ;
    tmp = ( tmp + MOD - 1 ) % MOD ;
    ans = ( ans * pow ( tmp , d [ i ] ) ) % MOD ;
    ans = ( ans * pow ( 2 , ( long ) ( d [ i ] - 1 ) * d [ i ] / 2 ) ) % MOD ;
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int [ ] a = new int [ n ] ; int [ ] d = new int [ n ] ; int dmax = 0 ; for ( int i = 0 ; i < n ; i ++ ) { a [ i ] = sc . nextInt ( ) ; d [ a [ i ] ] ++ ; dmax = Math . max ( a [ i ] , dmax ) ; } if ( a [ 0 ] != 0 || d [ 0 ] != 1 ) { System . out . println ( 0 ) ; return ; } for ( int i = 0 ; i <= dmax ; i ++ ) { if ( d [ i ] == 0 ) { System . out . println ( 0 ) ; return ; } } long ans = 1L ; for ( int i = 1 ; i <= dmax ; i ++ ) { long tmp = pow ( 2 , d [ i - 1 ] ) ; tmp = ( tmp + MOD - 1 ) % MOD ; ans = ( ans * pow ( tmp , d [ i ] ) ) % MOD ; ans = ( ans * pow ( 2 , ( long ) ( d [ i ] - 1 ) * d [ i ] / 2 ) ) % MOD ; } System . out . println ( ans ) ; }
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