Kata

Write a function that returns sum of second biggest and second lowest number of Array.

Array may includes Not a Numbers, or String numbers(!), you should ignore them.

If the sum is NaN return 0.

if in Array just one value and it is a Number you should return this number
if its Not a Number return 0

arr = [1,5,87,45,8,8]
 sum is 45 + 5 = 50
arr = ['str',3,5,7,2,'6']
 sum is 3 + 5 = 8 
because '6' is a string! And 'str' is also a string so they are both doesn't count
arr = [42]
 return 42
arr = ['4'] or ['4','a']
 return 0