question: public static long calculateServerFeeReverse ( long amount ) { long a = Constants . SERVER_FEE_FLAT ; long b = amount + a ; long c = ( long ) ( ( b / ( 1 - Constants . SERVER_FEE_PERCENTAGE ) ) - b ) ; return Math . min ( Constants . SERVER_FEE_MAX , Math . max ( Constants . SERVER_FEE_MIN , c + a ) ) ; }
target:  Calculate server fee reverse.