public static void main ( String [ ] args ) {
  Scanner scan = new Scanner ( System . in ) ;
  int N = scan . nextInt ( ) ;
  int M = scan . nextInt ( ) ;
  List < Integer > odd = new ArrayList < > ( ) ;
  List < Integer > even = new ArrayList < > ( ) ;
  for ( int i = 0 ;
  i < M ;
  ++ i ) {
    int a = scan . nextInt ( ) ;
    if ( a % 2 == 0 ) even . add ( a ) ;
    else odd . add ( a ) ;
  }
  if ( odd . size ( ) > 2 ) {
    System . out . println ( "Impossible" ) ;
    return ;
  }
  List < Integer > ans = new ArrayList < > ( ) ;
  if ( odd . size ( ) >= 1 ) {
    int d = odd . remove ( 0 ) ;
    System . out . print ( d + " " ) ;
    while ( d > 1 ) {
      ans . add ( 2 ) ;
      d -= 2 ;
    }
  }
  else {
    int d = even . remove ( 0 ) ;
    System . out . print ( d + " " ) ;
    ans . add ( d - 1 ) ;
  }
  for ( int i = 0 ;
  i < even . size ( ) ;
  ++ i ) {
    ans . add ( even . get ( i ) ) ;
    System . out . print ( even . get ( i ) + " " ) ;
  }
  if ( odd . size ( ) >= 1 ) {
    int d = odd . remove ( 0 ) ;
    System . out . print ( d + " " ) ;
    while ( d > 0 ) {
      ans . add ( 2 ) ;
      d -= 2 ;
    }
  }
  else {
    ans . add ( 1 ) ;
  }
  System . out . println ( ) ;
  System . out . println ( ans . size ( ) ) ;
  for ( int i : ans ) System . out . print ( i + " " ) ;
  System . out . println ( ) ;
}

public static void main ( String [ ] args ) { Scanner scan = new Scanner ( System . in ) ; int N = scan . nextInt ( ) ; int M = scan . nextInt ( ) ; List < Integer > odd = new ArrayList < > ( ) ; List < Integer > even = new ArrayList < > ( ) ; for ( int i = 0 ; i < M ; ++ i ) { int a = scan . nextInt ( ) ; if ( a % 2 == 0 ) even . add ( a ) ; else odd . add ( a ) ; } if ( odd . size ( ) > 2 ) { System . out . println ( " Impossible " ) ; return ; } List < Integer > ans = new ArrayList < > ( ) ; if ( odd . size ( ) >= 1 ) { int d = odd . remove ( 0 ) ; System . out . print ( d + " ▁ " ) ; while ( d > 1 ) { ans . add ( 2 ) ; d -= 2 ; } } else { int d = even . remove ( 0 ) ; System . out . print ( d + " ▁ " ) ; ans . add ( d - 1 ) ; } for ( int i = 0 ; i < even . size ( ) ; ++ i ) { ans . add ( even . get ( i ) ) ; System . out . print ( even . get ( i ) + " ▁ " ) ; } if ( odd . size ( ) >= 1 ) { int d = odd . remove ( 0 ) ; System . out . print ( d + " ▁ " ) ; while ( d > 0 ) { ans . add ( 2 ) ; d -= 2 ; } } else { ans . add ( 1 ) ; } System . out . println ( ) ; System . out . println ( ans . size ( ) ) ; for ( int i : ans ) System . out . print ( i + " ▁ " ) ; System . out . println ( ) ; }
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