def fun(X): 

    if len(X) == 0: 

        return (None,None) 

    else: 

        max = X[0] 

        min = X[0] 

        for a in X: 

            if a > max: 

                max = a 

            if a < min: 

                min = a 



        return (max,min) 



m=[11,33,6,67,34,4,3] 

fun(m)