The postfix record#1586
In postfix notation (also known as Reverse Polish Notation), the operator is written after its two operands. For example, the sum of two numbers and is written as . The notation B\ C\ +\ D\ * corresponds to the familiar expression (B + C) * D, and A\ B\ C\ +\ D\ *\ + means A + (B + C) * D. The advantage of postfix notation is that it does not require parentheses or additional operator precedence rules.
A single line contains an expression in postfix notation consisting of single-digit numbers and the operators , , . The string contains no more than numbers and operators in total.
Print the value of the given expression. It is guaranteed that the result of the expression and all intermediate calculation results (by absolute value) are less than 2^{31}.
Example 1