#include<iostream.h>
#include<fstream.h>

int fr(int i)
{
    int j, n;
    
    for (j=1; j<n; j++)
    {
        if (i%j==0)
        return 0;
    }
return 1;
}

int main ()
{
    int n,i,j=1,p;
    
    fstream f("fratii.in", ios::in);
    
    f>>n;
    
              
    for (i=1; i<=n; i++)
    {
        if (fr(i))
        p++;
    }
    
    

    ofstream g("fractii.out", ios::out);
    g<<p;

f.close();
g.close();

return 0;
}