def next_power_of_2(x):  
    return 1 if x == 0 else 2**(x - 1).bit_length()

def prev_power_of_2(x):
  return next_power_of_2(x) >> 1


print(', '.join(f'{x}:{next_power_of_2(x)}' for x in range(10)))
print(', '.join(f'{x}:{prev_power_of_2(x)}' for x in range(10)))