#include<stdio.h>
int n,c[10000000],i,nrdiv,d,numere;
int main ()
{
    freopen("ciur.in","rt",stdin);
    freopen("ciur.out","wt",stdout);
    scanf("%d",&n);
    i=1;
    d=1;
    nrdiv=0;
    numere=0;
    while(i<=n)
    {
        while(d<=i)
        {
            if(i%d==0)
            {
                nrdiv=nrdiv+1;
            }
            d=d+1;
        }
        if(nrdiv==2)
        {
            numere=numere+1;
        }
        nrdiv=0;
        d=1;
        i=i+1;
    }
    printf("%d",numere);
    fclose(stdin);
    fclose(stdout);
    return 0;
}