class IntList(list):
    def append(self,elem):
        if type(elem) is int:
            super().append(elem)
    pass

    def positive_sum(self):
        S=0
        for i in(self):
            if i>0:
                S+=i
        return S

    def negative_sum(self):
        S = 0
        for i in (self):
            if i < 0:
                S += i
        return S

    def insert(self,ind,elem):
        if type(elem) is int:
            super()[ind]=elem
        pass

    def extend(self,elem):
        if type(elem) is int:
            super().append(elem)
        pass