Protein Molecular Weight

Intermediate Proteins Mass Spectrometry Monoisotopic Mass
Significance:
Computing a protein's monoisotopic mass from its amino acid sequence is a routine calculation in mass-spectrometry-based proteomics — it's how software matches an observed peptide mass from a mass spec run back to a candidate protein sequence (peptide mass fingerprinting). This problem also introduces working with lookup tables of biochemical constants, a pattern you'll reuse constantly.
Statement

Given a protein string (using the standard 20 one-letter amino acid codes), compute its total **monoisotopic molecular weight** by summing the monoisotopic mass of each residue and adding the mass of one water molecule (18.01056 Da) to account for the two free termini. Round the final answer to **3 decimal places**.

**Monoisotopic mass table (Da), for reference:**
```
A: 71.03711 R: 156.10111 N: 114.04293 D: 115.02694 C: 103.00919
E: 129.04259 Q: 128.05858 G: 57.02146 H: 137.05891 I: 113.08406
L: 113.08406 K: 128.09496 M: 131.04049 F: 147.06841 P: 97.05276
S: 87.03203 T: 101.04768 W: 186.07931 Y: 163.06333 V: 99.06841
```

Sample Input
SKADYEK
Sample Output
839.402
Constraints

- `1 ≤ length(protein) ≤ 1000`
- Input contains only the 20 standard amino acid one-letter codes (no `X`, `*`, or ambiguity codes)

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Global Sequence Alignment with Affine Gap Penalty