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.
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Question: ['5215', 'c', '839', 'V']

Answer: 6054


Question: ['R', 'I', 'f', 'K', 'p', '8579', 'e', '1223', 'I', 'K', '8311', '2147', '4241', 'z', '6671', 'r']

Answer: 31172


Question: ['4869', 'L']

Answer:
4869