python-列表排重并列出重复项和重复项最小索引

list1=[10,11,12,11,12,13,15,13,14,15]
list2=[]
list3=[]
list4=[]
for i in list1:
    if i not in list2:
        list2.append(i)
    else:
        list3.append(i)
        list4.append(list1.index(i))
print(list2)
print(list3)
print(list4)