Given an array $A$ of $n$ integers. Count the number of even elements in array $A$.
### Input
- The first line contains an integer $n$.
- The second line contains $n$ integers $A_i$.
### Output
- A single integer representing the number of even elements.
### Constraints
- $1 \le n \le 10^5$.
- $1 \le A_i \le 10^9$.
### Sample test
```
4
3 4 5 1
```
Output:
```
1
```
