#include <stdio.h>
#include <stdlib.h>
FILE *f,*g;
int prim (int a)
{
    int i;
    for(i=2;i<=sqrt(a);i++)
        if(a%i==0)
            return 0;
    return 1;
}
int main()
{
    int i,j,n,nr=0,l;
    f=fopen("fractii.in","r");
    g=fopen("fractii.out","w");
    fscanf(f,"%d",&n);
    nr=n;
    for(i=2;i<=n;i++,nr+=n/log(n)+1){
        if(prim(i)==1)
            nr--;
    }
    fprintf(g,"%d",nr);
    return 0;
}