#include <iostream>
#include <cstdio>

using namespace std;

int prim(int x)
{
    int ct=0,i;
    for(i=1;i<=x;i++)
    {
        if(x%i==0)
        ct++;
        if(ct>=3)
        return 0;
    }
    return 1;
}

int main()
{
    int i,ct=0,n;
    freopen("ciur.in","r",stdin);
    freopen("ciur.out","w",stdout);
    scanf("%d",&n);
    if(prim(2)==1)
    ct++;
    for(i=3;i<=n;i+=2)
    {
        if(prim(i)==1)
        ct++;
    }
    printf("%d",ct);
    return 0;
}