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.

['R', 'C', 'S', 'x', '1529', 'r']
1529

['8755', 'A', '2893', '6703']
18351

['m', 'p', '3761', 'X', '7141', '5407', '7447', '8407', '1123', 'Q', '1101', 'q', 'Y', '1467', '4075', '9887', '5289', '1425']

56530