Задача А

n = int(input())
steps = [None] * (n + 2)
steps[0] = 0
steps[1] = 1
for i in range(2, n + 1):
    steps[i] = min(steps[i - 1], steps[i - 2]) + i % 10
print(steps[n])

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Задача С

n = int(input())
sequences = [None] * (n + 2)
sequences[0] = 1
sequences[1] = 3
for i in range(2, n + 1):
    sequences[i] = 2 * sequences[i - 1] + sequences[i - 2]
print(sequences[n])