#include <stdio.h>



int main()
{
long int n,i,j,m=0,k,l;
FILE* w,*r;

r=fopen("fractii.in","r");
fscanf(r,"%ld",&n);
for (i=1;i<=n;i++)
{
    k=i;
    m += i;
    for (j=2;j<=k;j++)
    {
        l=k%j;
        if (l==0)
        {
            m -= k/j;
            while ((k%j)==0)
                k=k/j;
        }
    }
}
fclose(r);
w=fopen("fractii.out","w");
fprintf(w,"%ld",2*m-1);
fclose(w);
return 0;
}