Iterates through p, identifying non-zero and non-repeating values, and returns them in a list Parameters
        ----------
        p: list of int

        Returns
        -------
        list of int

def ctc_label(p):
        """Iterates through p, identifying non-zero and non-repeating values, and returns them in a list Parameters
        ----------
        p: list of int

        Returns
        -------
        list of int
        """
        ret = []
        p1 = [0] + p
        for i, _ in enumerate(p):
            c1 = p1[i]
            c2 = p1[i+1]
            if c2 in (0, c1):
                continue
            ret.append(c2)
        return ret