№23 — #23156

from functools import lru_cache
import math
def cube_root_int(n):
    r = round(n ** (1 / 3))
    while (r + 1) ** 3 <= n:
        r += 1
    while r ** 3 > n:
        r -= 1
    return r if r ** 3 == n else None
@lru_cache(None)
def f(n, has77=False, has27=False, bused=False):
    if n == 6:
        return 1 if (has77 or has27) and bused else 0
    if n < 6:
        return 0
ans = 0
    ans += f(n - 6, has77 or n - 6 == 77, has27 or n - 6 == 27, bused)
x = int(math.isqrt(n))
    if x < n:
        ans += f(x, has77 or x == 77, has27 or x == 27, True)
if n > 9:
        x = n // 10
        ans += f(x, has77 or x == 77, has27 or x == 27, bused)
x = n // 2 if n % 2 == 0 else n - 9
    if x < n and x >= 1:
        ans += f(x, has77 or x == 77, has27 or x == 27, bused)
r = cube_root_int(n)
    if r is not None and r < n:
        ans += f(r, has77 or r == 77, has27 or r == 27, bused)
return ans
raw = f(777)
digits = sorted(map(int, str(raw)), reverse=True)
print(digits[0] + digits[1])