Reverse Polish notation (RPN) is a mathematical notation in which every operator follows all of its operands. It is also known as postfix notation and does not need any parentheses as long as each operator has a fixed number of operands. For example: \begin{itemize} \item the expression $2 + 4$ in RPN is represented like $2~4 +$ \item the expression $2 * 4 + 8$ in RPN is represented like $2~4 * 8 +$ \item the expression $2 * (4 + 8)$ in RPN is represented like $2~4~8 + *$ \end{itemize} Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are $+,~-,~*,~/$. Operator $/$ is an integer division $(14~/~3 = 4)$. Each operand may be an integer or another expression. \InputFile One line contains expression written in Reverse Polish notation. The length of expression is no more than $100$ symbols. \OutputFile Print the value of expression given in Reverse Polish notation.