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# Evaluate Expression

Problem Description

An arithmetic expression is given by a string array A of size N. Evaluate the value of an arithmetic expression in Reverse Polish Notation.

Valid operators are +, -, *, /. Each string may be an integer or an operator.

Problem Constraints

1 <= N <= 105

Input Format

The only argument given is string array A.

Output Format

Return the value of arithmetic expression formed using reverse Polish Notation.

Example Input
```Input 1:
A =   ["2", "1", "+", "3", "*"]
```

```Input 2:
A = ["4", "13", "5", "/", "+"]
```

Example Output
```Output 1:
9
```

```Output 2:
6
```

Example Explanation
```Explaination 1:
starting from backside:
* : () * ()
3 : () * (3)
+ : (() + ()) * (3)
1 : (() + (1)) * (3)
2 : ((2) + (1)) * (3)
((2) + (1)) * (3) = 9
```

```Explaination 2:
+ : () + ()
/ : () + (() / ())
5 : () + (() / (5))
13 : () + ((13) / (5))
4 : (4) + ((13) / (5))
(4) + ((13) / (5)) = 6
```

NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a question? Checkout Sample Codes for more details.
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## Discussion

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