An organic compound P having molecular formula \( \mathrm{C}_{6}\mathrm{H}_{6}\mathrm{O}_{3} \) gives ferric chloride test and does not have intramolecular hydrogen bond. The compound P reacts with \( 3 \) equivalents of \( \mathrm{NH}_{2}\mathrm{OH} \) to produce oxime Q. Treatment of P with excess methyl iodide in the presence of \( \mathrm{KOH} \) produces compound R as the major product. Reaction of R with excess iso-butylmagnesium bromide followed by treatment with \( \mathrm{H}_{3}\mathrm{O}^{+} \) gives compound S as the major product.
The total number of methyl (\( -\mathrm{CH}_{3} \)) group(s) in compound S is______.
