public static void main ( String [ ] args ) {
  BigDecimal x1 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ;
  BigDecimal y1 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ;
  BigDecimal x2 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ;
  BigDecimal y2 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ;
  BigDecimal x3 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ;
  BigDecimal y3 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ;
  double c = 0 ;
  BigDecimal bd = new BigDecimal ( c ) ;
  BigDecimal two = new BigDecimal ( 2.0 ) ;
  bd = x1 . multiply ( y2 ) . add ( x2 . multiply ( y3 ) ) . add ( x3 . multiply ( y1 ) ) . subtract ( y1 . multiply ( x2 ) ) . subtract ( y2 . multiply ( x3 ) ) . subtract ( y3 . multiply ( x1 ) ) . divide ( two ) ;
  bd . setScale ( 3 , BigDecimal . ROUND_HALF_UP ) ;
  System . out . println ( bd . abs ( ) ) ;
  System . out . flush ( ) ;
  sc . close ( ) ;
}

public static void main ( String [ ] args ) { BigDecimal x1 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ; BigDecimal y1 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ; BigDecimal x2 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ; BigDecimal y2 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ; BigDecimal x3 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ; BigDecimal y3 = new BigDecimal ( Integer . parseInt ( sc . next ( ) ) ) ; double c = 0 ; BigDecimal bd = new BigDecimal ( c ) ; BigDecimal two = new BigDecimal ( 2.0 ) ; bd = x1 . multiply ( y2 ) . add ( x2 . multiply ( y3 ) ) . add ( x3 . multiply ( y1 ) ) . subtract ( y1 . multiply ( x2 ) ) . subtract ( y2 . multiply ( x3 ) ) . subtract ( y3 . multiply ( x1 ) ) . divide ( two ) ; bd . setScale ( 3 , BigDecimal . ROUND_HALF_UP ) ; System . out . println ( bd . abs ( ) ) ; System . out . flush ( ) ; sc . close ( ) ; }
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