Compounds Containing Nitrogen

Identify substrate '\(\mathrm{A}\)' in the following conversion.

\(\mathrm{A}+\underset{\text { (excess) }}{\mathrm{CH}_3 \mathrm{I}} \stackrel{\Delta}{\longrightarrow} {\mathrm{C}_2 \mathrm{H}_5}\left(\mathrm{CH}_3\right)_3 \stackrel{+}{\mathrm{N}} \mathrm{I}^{-}\)