一个关于素数变化的题目，输入一对素数，每个是4位数，每次只能变化一位数，且变化后的数还是素数，求经过多少次变化，能变成另一个输入的素数-A prime number changes on the subject, enter a pair of prime numbers, each is a 4-digit, each only a few changes, and changes in the number of post-prime, or seeking many times the c