public class Solution {
    public int evalRPN(String[] tokens) {
        Stack<Integer> s = new Stack<Integer>();
        String operators = "+-*/";
        for(String token : tokens){
            if(!operators.contains(token)){
                s.push(Integer.valueOf(token));
                continue;
            }

            int a = s.pop();
            int b = s.pop();
            if(token.equals("+")) {
                s.push(b + a);
            } else if(token.equals("-")) {
                s.push(b - a);
            } else if(token.equals("*")) {
                s.push(b * a);
            } else {
                s.push(b / a);
            }
        }
        return s.pop();
    }
}