public static void solve ( ) throws Exception {
  int n = in . nextInt ( ) ;
  int m = in . nextInt ( ) ;
  int freq [ ] = new int [ m ] ;
  long totalBooks = 0 ;
  for ( int i = 0 ;
  i < n ;
  ++ i ) {
    freq [ in . nextInt ( ) - 1 ] ++ ;
    totalBooks ++ ;
  }
  long ans = ( totalBooks * ( totalBooks - 1 ) ) / 2 ;
  for ( int i = 0 ;
  i < m ;
  ++ i ) {
    ans -= ( ( long ) freq [ i ] * ( freq [ i ] - 1 ) ) / 2 ;
  }
  out . println ( ans ) ;
}

public static void solve ( ) throws Exception { int n = in . nextInt ( ) ; int m = in . nextInt ( ) ; int freq [ ] = new int [ m ] ; long totalBooks = 0 ; for ( int i = 0 ; i < n ; ++ i ) { freq [ in . nextInt ( ) - 1 ] ++ ; totalBooks ++ ; } long ans = ( totalBooks * ( totalBooks - 1 ) ) / 2 ; for ( int i = 0 ; i < m ; ++ i ) { ans -= ( ( long ) freq [ i ] * ( freq [ i ] - 1 ) ) / 2 ; } out . println ( ans ) ; }
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