Complex sentence: With a length of (including the White Main:), it is the longest right tributary of the Rhine, and the longest river lying entirely in Germany (if the Weser and the Werra are considered as two separate rivers; together they are longer).
Split into simpler sentences: With a length of, including the White Main as, it is the longest right tributary of the Rhine. It is also the longest river lying entirely in Germany (if the Weser and the Werra are considered as two separate rivers; together they are longer).