How many of given are essential athino acids?
Glycine, Alanine, Valine, Leucine, Proline, Methionine.

Explanation

To determine how many of the given amino acids are essential, we first need to identify which of the listed amino acids are classified as essential.

### Step-by-Step Solution:

1. **List the Given Amino Acids**:
- Glycine
- Alanine
- Valine
...