#5_3
list1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
print("start list", list1)

a = list1[9]
b = list1[8]
c = list1[7]

list1 = [c] + [b] + [a] + list1
list1.pop(-1)
list1.pop(-1)
list1.pop(-1)

print("new list", list1)
print()
print()

#5_4
#a
word = "DONAUDAMPFSCHIFFAHRTSGESELLSCHAFTSSTEWARDESS"
letters = list(word)
print(letters)
print("length:", len(letters))

#b
letters_once = []
for element in letters:
    if element not in letters_once:
        letters_once.append(element)

print(letters_once)
print("length new:", len(letters_once))

print()
print()

#5_5
def sort(list2):
    list2.sort(key = lambda x: x[1])
    return list2

list2 = [[1, 2, 3], [2, 1, 3], [4, 0, 1]]
print(sort(list2))