class Tetel():
    def __init__(self, f):
        # input file
        self.f = f

        def _process_data(fl):
            data = []
            with open(fl) as f:
                for sz in f:
                        data.append(int(sz))
            return data

        def _get_max(data):
            """returns maximum of a list"""
            return max(data)

        def _get_sum(data):
            """returns sum of a list"""
            return sum(data)

        def _filter_data(data, f):
            """returns elements of a list that return True to a function"""
            return [elem for elem in data if f(elem)]

        self.data = _process_data(self.f)
        self.get_max = _get_max
        self.get_sum = _get_sum
        self.filter_data = _filter_data

    def osszegez(self):
        """returns sum"""
        return self.get_sum(self.data)

    def maxker(self):
        """returns max"""
        return self.get_max(self.data)

    def feltmaxker(self, f):
        """returns max of filter_data's returned list"""
        return self.get_max(self.filter_data(self.data, f))

    def szamlal(self, f):
        """returns length of filter_data's returned list"""
        return len(self.filter_data(self.data, f))

print dir(Tetel("in"))