21 обязательная 10

dp = [0] * 13
dp[3] = 1
for i in range(4, 11):
    dp[i] = dp[i - 1] + dp[i - 2]
    if i % 2 == 0:
        dp[i] += dp[i // 2]
for i in range(11, 13):
    dp[i] = dp[i - 1]
    if i - 2 >= 10:
        dp[i] += dp[i - 2]
    if i % 2 == 0 and i // 2 >= 10:
        dp[i] += dp[i // 2]
print(dp[12])