Evaluate Reverse Polish Notation

Evaluate an arithmetic expression given in Reverse Polish Notation. Valid operators are `+`, `-`, `*`, and `/`. Each operand is an integer. Division truncates toward zero. Input format: - First line: n - Second line: n space-separated tokens Print the integer result.

1 <= n <= 10^5
The expression is valid.
Every intermediate value and the result fit in a signed 64-bit integer.
Division never uses a zero divisor.

5
2 1 + 3 *

9

5
4 13 5 / +

6