hrw最近在看科幻小说《三体》，被小说里面深厚的历史渊源和宏伟壮阔的奇思构想深深的吸引住了
其中有一个章节讲到截取“审判号”巨型游轮上的残留的三体密码，然而想要得到密码，必须破解一些
相应的关卡，只见密码室的门口写着：
give you two prime number n,m(1000<n,m<9999),find the short path let n change to m,and notice that in the every step,the change number must also be a prime and every step you can only change one digit Here is a solution in the case above.
n=1009,m=1033
1009
1039
1033
The step of this solution is 2 Note that the first step we can ignore
if you can solve this problem ,the key of the《threebody》you will get !