public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int n = sc . nextInt ( ) ;
  int k = sc . nextInt ( ) ;
  int [ ] val = new int [ n + 1 ] ;
  Sushi [ ] box = new Sushi [ n ] ;
  ArrayList < Long > list = new ArrayList < Long > ( ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    int t = sc . nextInt ( ) ;
    long d = sc . nextLong ( ) ;
    box [ i ] = new Sushi ( t , d ) ;
  }
  Arrays . sort ( box , Comparator . comparing ( Sushi :: getD ) . reversed ( ) ) ;
  long sum = 0 ;
  long vali = 0 ;
  for ( int i = 0 ;
  i < k ;
  i ++ ) {
    sum += box [ i ] . d ;
    if ( val [ box [ i ] . t ] == 0 ) {
      vali ++ ;
    }
    else {
      list . add ( box [ i ] . d ) ;
    }
    val [ box [ i ] . t ] ++ ;
  }
  long ans = vali * vali + sum ;
  if ( list . size ( ) == 0 ) {
    System . out . println ( ans ) ;
    return ;
  }
  int min = list . size ( ) - 1 ;
  for ( int i = k ;
  i < n ;
  i ++ ) {
    if ( val [ box [ i ] . t ] == 0 ) {
      vali ++ ;
      val [ box [ i ] . t ] ++ ;
      sum += box [ i ] . d - list . get ( min ) ;
      min -- ;
      ans = Math . max ( ans , vali * vali + sum ) ;
      if ( min == - 1 ) {
        break ;
      }
    }
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int n = sc . nextInt ( ) ; int k = sc . nextInt ( ) ; int [ ] val = new int [ n + 1 ] ; Sushi [ ] box = new Sushi [ n ] ; ArrayList < Long > list = new ArrayList < Long > ( ) ; for ( int i = 0 ; i < n ; i ++ ) { int t = sc . nextInt ( ) ; long d = sc . nextLong ( ) ; box [ i ] = new Sushi ( t , d ) ; } Arrays . sort ( box , Comparator . comparing ( Sushi :: getD ) . reversed ( ) ) ; long sum = 0 ; long vali = 0 ; for ( int i = 0 ; i < k ; i ++ ) { sum += box [ i ] . d ; if ( val [ box [ i ] . t ] == 0 ) { vali ++ ; } else { list . add ( box [ i ] . d ) ; } val [ box [ i ] . t ] ++ ; } long ans = vali * vali + sum ; if ( list . size ( ) == 0 ) { System . out . println ( ans ) ; return ; } int min = list . size ( ) - 1 ; for ( int i = k ; i < n ; i ++ ) { if ( val [ box [ i ] . t ] == 0 ) { vali ++ ; val [ box [ i ] . t ] ++ ; sum += box [ i ] . d - list . get ( min ) ; min -- ; ans = Math . max ( ans , vali * vali + sum ) ; if ( min == - 1 ) { break ; } } } System . out . println ( ans ) ; }
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