#include <fstream>
#define MAX 1000005
FILE *f=fopen("fractii.in","r");
FILE *g=fopen("fractii.out","w");
long v[MAX];
int main()
{
    long long n,i,j,nr=0;
     
    fscanf(f,"%lld",&n);
    for (i=1;i<=n;i++)
     v[i]=i-1;
    for (i=2;i<=n;i++)
     for (j=2*i;j<=n;j+=i)
         v[j]-=v[i];
    for (i=2;i<=n;i++)
     nr+=v[i];
    fprintf(g,"%lld",nr*2+1);
    fclose(f);
    fclose(g);
    return 0;
}