\[\boxed{\ \mathbf{453}.}\]
\[(a + 253) \cdot 7 < (9864 - a)\ :4\]
\[a = 124:\]
\[(124 + 253) \cdot 7 < (9864 - 124)\ :4\]
\[377 \cdot 7 < 9740\ :4\]
\[Неверно:\]
\[2639 > 2435.\]