Given an array of tokens in Reverse Polish Notation, evaluate the expression and return the integer result.
Examples
Input:["2","1","+","3","*"]
Output:9
Input:["4","13","5","/","+"]
Output:6
Hints
Initialize an empty stack to store operands.
When encountering an operator, pop the top two elements from the stack, apply the operator (second popped element operator first popped element), and push the result back onto the stack.
Handle division carefully by converting operands to integers before division to ensure truncation toward zero, and push the result back onto the stack.