def f(x, h):

delit = [k for k in range(2, 10) if x % k == 0]

if x <= 15:

return h % 2 == 0

elif h == 0:

return 0

elif not any(x % k == 0 for k in range(2, 10)):

x -= 1

elif (h-1)%2 ==0:

return any(f(x-k, h-1) for k in delit)

else:

return all(f(x-k, h-1) for k in delit)

for x in range(16, 100):

if not (f(x,2)) and f(x,4):

print('За­да­ча 21:',x)

break