The String $p\ r\ q \rightarrow \neg q \triangle p \rightarrow \wedge$

Essay

The string $p\ r\ q \rightarrow \neg q \triangle p \rightarrow \wedge$ is postfix notation for a logic expression; however, there is a misprint. The triangle should be one of these three: $r , V , Or \neg$ Determine which of these three it must be and explain your reasoning.