BX$07$

$"$ c# $$

A $$ B $1$

$$

$$

$(250)$ nonnegative integers $1,2,...,\text{'}$th $1000$

$$

$""""(1)$

$11$

$3$

$143$

$$

$12$

$23$

$23$

$23$

$22$

$3$

$111$

$$

$"$