static decimal GetPrice(IEnumerable<Products> products, IDictionary<Products, decimal> prices)
        {
            var grouping = products.ToLookup(l => l);
            var ab = FullSetCount(List(grouping[Products.A], grouping[Products.B])) * 0.1m;
            var de = FullSetCount(List(grouping[Products.D], grouping[Products.E])) * 0.05m;
            var efg = FullSetCount(List(grouping[Products.E], grouping[Products.F], grouping[Products.G])) * 0.05m;
            var aAndklm = products
                .Where(p => p == Products.K || p == Products.L || p == Products.M)
                .Take(grouping[Products.A].Count())
                .Aggregate(0m, (acc, p) => acc + prices[p] * 0.05m);
            decimal onCount;
            switch (products.Except(List(Products.A, Products.B)).Count())
            {
                case var c when c < 3:
                    onCount = 1m;
                    break;
                case 3:
                    onCount = 0.95m;
                    break;
                case 4:
                    onCount = 0.90m;
                    break;
                case var c when c >= 5:
                    onCount = 0.95m;
                    break;
                default:
                    onCount = 1m;
                    break;
            }

            var initalSum = products.Sum(p => prices[p]);
            var result = (initalSum - ab - de - efg - aAndklm) * onCount;
            return result;
        }

        static int FullSetCount<T>(params IEnumerable<T>[] cols)
        {
            return cols.Select(c => c.Count()).Min();
        }

        static IEnumerable<T> List<T>(params T[] items) => items;