public static void main ( String [ ] args ) {
  Scanner scan = new Scanner ( System . in ) ;
  int R = scan . nextInt ( ) ;
  int C = scan . nextInt ( ) ;
  int K = scan . nextInt ( ) ;
  int N = scan . nextInt ( ) ;
  int [ ] [ ] p = new int [ N ] [ 2 ] ;
  int [ ] row = new int [ R + 1 ] ;
  int [ ] col = new int [ C + 1 ] ;
  Arrays . fill ( row , 0 ) ;
  Arrays . fill ( col , 0 ) ;
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    int r = scan . nextInt ( ) ;
    int c = scan . nextInt ( ) ;
    p [ i ] [ 0 ] = r ;
    p [ i ] [ 1 ] = c ;
    row [ r ] ++ ;
    col [ c ] ++ ;
  }
  scan . close ( ) ;
  int [ ] row1 = new int [ 100000 + 1 ] ;
  int [ ] col1 = new int [ 100000 + 1 ] ;
  Arrays . fill ( row1 , 0 ) ;
  Arrays . fill ( col1 , 0 ) ;
  for ( int i = 1 ;
  i <= R ;
  i ++ ) {
    row1 [ row [ i ] ] ++ ;
  }
  for ( int i = 1 ;
  i <= C ;
  i ++ ) {
    col1 [ col [ i ] ] ++ ;
  }
  long cnt = 0 ;
  for ( int i = 0 ;
  i <= K ;
  i ++ ) {
    cnt += row1 [ i ] * col1 [ K - i ] ;
  }
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    if ( row [ p [ i ] [ 0 ] ] + col [ p [ i ] [ 1 ] ] == K ) {
      cnt -- ;
    }
    else if ( row [ p [ i ] [ 0 ] ] + col [ p [ i ] [ 1 ] ] == K + 1 ) {
      cnt ++ ;
    }
  }
  System . out . println ( cnt ) ;
}

public static void main ( String [ ] args ) { Scanner scan = new Scanner ( System . in ) ; int R = scan . nextInt ( ) ; int C = scan . nextInt ( ) ; int K = scan . nextInt ( ) ; int N = scan . nextInt ( ) ; int [ ] [ ] p = new int [ N ] [ 2 ] ; int [ ] row = new int [ R + 1 ] ; int [ ] col = new int [ C + 1 ] ; Arrays . fill ( row , 0 ) ; Arrays . fill ( col , 0 ) ; for ( int i = 0 ; i < N ; i ++ ) { int r = scan . nextInt ( ) ; int c = scan . nextInt ( ) ; p [ i ] [ 0 ] = r ; p [ i ] [ 1 ] = c ; row [ r ] ++ ; col [ c ] ++ ; } scan . close ( ) ; int [ ] row1 = new int [ 100000 + 1 ] ; int [ ] col1 = new int [ 100000 + 1 ] ; Arrays . fill ( row1 , 0 ) ; Arrays . fill ( col1 , 0 ) ; for ( int i = 1 ; i <= R ; i ++ ) { row1 [ row [ i ] ] ++ ; } for ( int i = 1 ; i <= C ; i ++ ) { col1 [ col [ i ] ] ++ ; } long cnt = 0 ; for ( int i = 0 ; i <= K ; i ++ ) { cnt += row1 [ i ] * col1 [ K - i ] ; } for ( int i = 0 ; i < N ; i ++ ) { if ( row [ p [ i ] [ 0 ] ] + col [ p [ i ] [ 1 ] ] == K ) { cnt -- ; } else if ( row [ p [ i ] [ 0 ] ] + col [ p [ i ] [ 1 ] ] == K + 1 ) { cnt ++ ; } } System . out . println ( cnt ) ; }
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