public static void main ( String args [ ] ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int k = sc . nextInt ( ) ;
  int [ ] a = new int [ k ] ;
  for ( int i = 0 ;
  i < k ;
  i ++ ) a [ i ] = sc . nextInt ( ) ;
  int [ ] b = Arrays . copyOf ( a , k ) ;
  Arrays . sort ( b ) ;
  int total = n * k + 1 ;
  int [ ] available = new int [ total ] ;
  int count = 0 ;
  for ( int i = 1 ;
  i <= total ;
  i ++ ) {
    if ( Arrays . binarySearch ( b , i ) < 0 ) {
      available [ count ] = i ;
      count ++ ;
    }
  }
  count = 0 ;
  for ( int i = 0 ;
  i < k ;
  i ++ ) {
    System . out . print ( a [ i ] + " " ) ;
    for ( int j = 0 ;
    j < n - 1 ;
    j ++ ) {
      System . out . print ( available [ count ++ ] + " " ) ;
    }
    System . out . println ( "" ) ;
  }
}

public static void main ( String args [ ] ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int k = sc . nextInt ( ) ; int [ ] a = new int [ k ] ; for ( int i = 0 ; i < k ; i ++ ) a [ i ] = sc . nextInt ( ) ; int [ ] b = Arrays . copyOf ( a , k ) ; Arrays . sort ( b ) ; int total = n * k + 1 ; int [ ] available = new int [ total ] ; int count = 0 ; for ( int i = 1 ; i <= total ; i ++ ) { if ( Arrays . binarySearch ( b , i ) < 0 ) { available [ count ] = i ; count ++ ; } } count = 0 ; for ( int i = 0 ; i < k ; i ++ ) { System . out . print ( a [ i ] + " ▁ " ) ; for ( int j = 0 ; j < n - 1 ; j ++ ) { System . out . print ( available [ count ++ ] + " ▁ " ) ; } System . out . println ( " " ) ; } }
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