In this task, you are given an input list A. You need to find all the elements of the list that are numbers and calculate their sum.

['1305', '1673', 'w']
2978

['R', 'k', '3355', 'Y', '6635', 'M', '4839', 'T', 'd', '495', 'g', 'E', 'g', 'F', 'S', '5377', 'g']
20701

['f', 'a', 'u', '8829']

8829