TASK DEFINITION: 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.
PROBLEM: ['K', '4403', 'a', '3881', '4139', 'w', '1861', 'G']

SOLUTION: 14284

PROBLEM: ['o', '8089', '2159', '943', '1255', 'w', 'Y', '3723', 'n', '7767', '2209', 'F', 'c', 'J', '5259', '4427', 'n', 'U']

SOLUTION: 35831

PROBLEM: ['9105', 'S', 'k', 'P', 'W', 'X', '803', 'K', 'u', 'a', 'P', 'd', 'g', '8505']

SOLUTION:
18413