public static void taskSolver ( FastReader sc ) {
  int n = sc . nextInt ( ) ;
  int arr [ ] = new int [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) arr [ i ] = sc . nextInt ( ) ;
  int ans = 0 ;
  Arrays . sort ( arr ) ;
  for ( int i = 1 ;
  i <= n ;
  i += 2 ) {
    ans += Math . abs ( arr [ i ] - arr [ i - 1 ] ) ;
  }
  System . out . println ( ans ) ;
}

public static void taskSolver ( FastReader sc ) { int n = sc . nextInt ( ) ; int arr [ ] = new int [ n ] ; for ( int i = 0 ; i < n ; i ++ ) arr [ i ] = sc . nextInt ( ) ; int ans = 0 ; Arrays . sort ( arr ) ; for ( int i = 1 ; i <= n ; i += 2 ) { ans += Math . abs ( arr [ i ] - arr [ i - 1 ] ) ; } System . out . println ( ans ) ; }
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