Τhey mature physically more, but not mentally. That is becasue mental maturity is absed on other factor such as personality and various situations one can be in at certain periods of one's life
The length of the Amur (Heilongjiang) is 5,498 km (3,417 miles). It is the 8th longest river in the world. SOURCE: S. Liu, P. Lu, D. Liu, P. Jin, W. Wang, Pinpointing the sources and measuring the lengths of the principal rivers of the world, International Journal of Digital Earth, Volume 2, Issue 1 March 2009 , pages 80 - 87,DOI: 10.1080/17538940902746082