def find_average(mark_list):
    
          total=0
          try:
              for i in range(0, len(mark_list)):
                       total+=mark_list[i]
              marks_avg=total/len(mark_list)
              return marks_avg
          except NameError:
              print("Name Error")
          except ValueError:
              print("Value Error")
          except TypeError:
              print("Type Error")
          
m_list=[1,2,3,4]
m_list=[1,2,3,"4"]
print("Average marks:", find_average(m_list))