The three natural numbers 456, 466, and 476 are respectively subtracted from the same positive integer a, and the differences obtained are all prime numbers, then a=how much.
456、466、476三个自然数，分别减去同一个正整数a，得到的差均为质数，则a=多少．
<gadget id="calculator">456 - 3</gadget>
<output>453</output>

<result>453</result>