#include  <fstream>
#include <bitset>
#include<math.h>
using namespace std;
bitset <2000005>ciur;
ifstream cin("dk.in");
ofstream cout("dk.out");
long n;
    int main() 
{
    int i,j, contor=0;
    float radical;
 for(i=4;i<=400000;i+=2)  ciur[i]=1;


for(i=3; i<=400000; i=i+2)
             for (j=i+i;j<=400000;j=j+i)
                                   ciur[j]=1; 

    while(cin>>n)
      if(ciur[n]==0)
        contor++;        
    cout<<contor<<"\n";
    return 0;
}