import java.util.*;

public class Solution {
     public int evalRPN(String[] tokens)
    {
        Stack<Integer> stack = new Stack<>();
        for(int i=0;i<tokens.length;i++)
        {
            try
            {
                int num = Integer.parseInt(tokens[i]);
                stack.add(num);
            }
            catch (Exception e)
            {
                int b = stack.pop();
                int a = stack.pop();
                stack.add(get(a,b,tokens[i]));
            }
        }

        return stack.pop();
    }

    private int get(int a, int b, String operator)
    {
        switch (operator)
        {
            case "+":
                return a+b;
            case "-":
                return a-b;
            case "*":
                return a*b;
            case "/":
                return a/b;
            default:
                return 0;
        }
    }
}