heros=["spider man", "thor", "hulk", "iron man", "captain america"]
print(len(heros))
heros.append("black panther")
print(heros)
heros.remove("black panther")
heros.insert(3,"black panther")
print(heros)
heros[1:3]= ["doctor strange"]
heros.sort()
print(heros)