Transition function of a Pushdown Automaton maps a $3-$tuple $($q$,$A$,$B$)$ to a $2-$tuple $($p$,$C$),$ where $\text{'}$q$\text{'}$ is the state before the transition, and $\text{'}$p$\text{'}$ is the state after the transition. A belongs to the input alphabet of the automaton. After we reach to the state $\text{'}$p$\text{'},$