public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  n = Integer . parseInt ( sc . next ( ) ) ;
  k = Integer . parseInt ( sc . next ( ) ) ;
  long [ ] hori = new long [ n ] ;
  long [ ] vert = new long [ n ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) vert [ i ] = Long . parseLong ( sc . next ( ) ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) hori [ i ] = Long . parseLong ( sc . next ( ) ) ;
  Arrays . sort ( vert ) ;
  Arrays . sort ( hori ) ;
  long hi = hori [ n - 1 ] * vert [ n - 1 ] ;
  long lo = hori [ 0 ] * vert [ 0 ] - 1 ;
  long mid ;
  while ( hi - lo > 1 ) {
    mid = ( hi + lo ) / 2 ;
    if ( check ( vert , hori , mid ) ) hi = mid ;
    else lo = mid ;
  }
  System . out . println ( hi ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; n = Integer . parseInt ( sc . next ( ) ) ; k = Integer . parseInt ( sc . next ( ) ) ; long [ ] hori = new long [ n ] ; long [ ] vert = new long [ n ] ; for ( int i = 0 ; i < n ; i ++ ) vert [ i ] = Long . parseLong ( sc . next ( ) ) ; for ( int i = 0 ; i < n ; i ++ ) hori [ i ] = Long . parseLong ( sc . next ( ) ) ; Arrays . sort ( vert ) ; Arrays . sort ( hori ) ; long hi = hori [ n - 1 ] * vert [ n - 1 ] ; long lo = hori [ 0 ] * vert [ 0 ] - 1 ; long mid ; while ( hi - lo > 1 ) { mid = ( hi + lo ) / 2 ; if ( check ( vert , hori , mid ) ) hi = mid ; else lo = mid ; } System . out . println ( hi ) ; }
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