#include <iostream.h>
                  int pream(int n)
                  {

                     int i;
                     for(i=2;i<=n-1;i++)

                             if(n%i==0) break;
                     if(i<=n-1)return 0;
                     else return 1;
                  }
                  void main()
                 {
                     cout<<"请输入一个数"<<endl;
                     int a;
                     cin>>a;
                     if(pream(a))cout<<"是素数"<<endl;
                     else cout<<"不是素数"<<endl;

                  }