Given an array, return the difference between the count of even numbers and the count of odd numbers. `0` will be considered an even number. 
```
For example:
solve([0,1,2,3]) = 0 because there are two even numbers and two odd numbers. Even - Odd = 2 - 2 = 0.  
```
Let's now add two letters to the last example: 
```
solve([0,1,2,3,'a','b']) = 0. Again, Even - Odd = 2 - 2 = 0. Ignore letters. 
```
The input will be an array of lowercase letters and numbers only. 
In some languages (Haskell, C++, and others), input will be an array of strings:
```
solve ["0","1","2","3","a","b"] = 0 
```
Good luck!
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def solve(a):
    return sum( isinstance(x, int) and [1, -1][x % 2] for x in a )
def solve(a):
    return sum( isinstance(x, int) and [1, -1][x % 2] for x in a )