【PAT】1015. Reversible Primes

#define LOCAL
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
using namespace std;

typedef long long ll;
int a[1000100];
bool isprime(int x){
    for(int i=2;i*i<=x;i++){
        if(x%i==0) return false;
    }
    if(x==0 || x==1) return false;
    else
    return true;
}
int main()
{
    #ifdef LOCAL
        freopen("data.in","r",stdin);
        freopen("data.out","w",stdout);
    #endif // LOCAL
    int n,r;
    int d[111]={0};
    while(scanf("%d",&n)!=EOF){
        if(n<0) break;
        scanf("%d",&r);
        int len=0;
        int ans=n;
        while(n){
            d[len++]=n%r;
            n/=r;
        }

        for(int i=0;i<len;i++){
            n=n*r+d[i];
        }
        if(isprime(n)&&isprime(ans)) cout<<"Yes"<<endl;
        else cout<<"No"<<endl;
    }


    return 0;
}