题目的意思是：给出一个数N和一个基数D。首先这个数必须是素数。其次，将这个数（1）转为D进制数（2）将这个D进制数反转（3）将反转后的数再转为十进制数，这个十进制数依然是素数。 这样我们就输出“Yes”。

判断素数：一个数N，如果从2到sqrt(N)都不存在因子，则认为这个数是素数。 注意：0和1不是素数。

将十进制数转为n进制数：（待补充。。。）

A reversible prime in any number system is a prime whose "reverse" in that number system is also a prime. For example in the decimal system 73 is a reversible prime because its reverse 37 is also a prime.

Now given any two positive integers N (< 105) and D (1 < D <= 10), you are supposed to tell if N is a reversible prime with radix D.

Input Specification:

The input file consists of several test cases. Each case occupies a line which contains two integers N and D. The input is finished by a negative N.

Output Specification:

For each test case, print in one line "Yes" if N is a reversible prime with radix D, or "No" if not.

Sample Input:
73 10
23 2
23 10
-2
Sample Output:
Yes
Yes
No

#include
#include
#include
using namespace std;

bool is_Prime(int a)
{
	int i;
	if(a==0 || a==1) return false;

	//注意是i<=sqrt(),之前弄成i>N){
		if( N<0 ) break;
		cin>>D;
	    if( is_Prime(N) && is_Prime( change(N,D) )){
			cout<<"Yes"<