How do I calculate the time complexity of this recursive function which halves the input value or halves it and then adds the input value?

Question

I am having difficulties determining the time complexity of the code below:

int func(int n) { // n > 0
    if (n < 2) {
         return 1;
    } else if (n % 2 == 0) {
         return func(n / 3);
    } else {
         return func(n / 3) + n;
    }
}

I have attempted to approach this question using Master Theorem, so I have tried to break it down into:

n = size of input
a = number of sub-problems in the recursion = 3
n/b = size of each sub-problem
f(n) = cost of the work done outside the recursive call

However, I am struggling to understand how to determine the size of each sub-problem and f(n) - the cost of the work done outside the recursive call. At the moment I am just assuming that we take the greater time complexity of the if/else statement so the time complexity would be O(logn).

Also, does the '+ n' in the else statement affect the time complexity of this function?

Any help to understand this would be greatly appreciated!