#include <fstream>
using namespace std;
#define MAX 1000001
FILE *f=fopen("fractii.in","r");
FILE *g=fopen("fractii.out","w");
int v[MAX];
int main()
{
    int n,i,j;
    long long nr=0;
    fscanf(f,"%d",&n);
    for (i=1;i<=n;i++)
        v[i]=i;
    for (i=2;i<=n;i++)
    {
        if (v[i]==i)
            for (j=i;j<=n;j+=i)
                v[j]/=i, v[j] *= (i-1);
        nr+=v[i];
    }
    fprintf(g,"%lld",(nr<<1)+1);
    fclose(f);
    fclose(g);
    return 0;
}