public void Part1Test()
        {
            // Given
            var cypher = new XmasCypher(Input.GetLines(9).Select(BigInteger.Parse))
            {
                PreambleSize = 5
            };

            // When
            var nonSumNumber = cypher.FindNonSumNumber();

            // Then
            Assert.Equal(127, nonSumNumber);
        }
        public void Part2Test()
        {
            // Given
            var cypher = new XmasCypher(Input.GetLines(9).Select(BigInteger.Parse))
            {
                PreambleSize = 5
            };

            // When
            var key = cypher.FindKey(cypher.FindNonSumNumber()).ToArray();

            // Then
            Assert.Equal(15, key.Min());
            Assert.Equal(47, key.Max());
        }