#include <iostream>

using namespace std;

int main()
{
    int x,prime=0,count=0;
    
    cin >> x;
    
    for (int j=1; j<=x; j++)
    {
        for (int i=1; i<=x; i++)
        {
            if(j%i==0)
              count+=1;
        }
        if (count==2)
           prime+=1;
        
        count=0;
    }
    
     cout << prime;  
        
    return 0;    
}