a = [7,8,[[9,8],[2,6], 7], [11], [[7,9,[12,15],3]]]
def find_max(my_list):
m = max([find_max(x) if type(x) is list else x for x in my_list])
return m
print(find_max(a))
YSA9IFs3LDgsW1s5LDhdLFsyLDZdLCA3XSwgWzExXSwgW1s3LDksWzEyLDE1XSwzXV1dCgpkZWYgZmluZF9tYXgobXlfbGlzdCk6CiAgICBtID0gbWF4KFtmaW5kX21heCh4KSBpZiB0eXBlKHgpIGlzIGxpc3QgZWxzZSB4IGZvciB4IGluIG15X2xpc3RdKQogICAgcmV0dXJuIG0KCnByaW50KGZpbmRfbWF4KGEpKQ==