#include <stdio.h>

using namespace std;

FILE *f=fopen("fractii.in","r");
FILE *g=fopen("fractii.out","w");

long long v[1000001],s;
int i,j,n;

int main()
{
    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]=v[j]/i*(i-1);
s=0;
for(i=2;i<=n;i++)
s+=v[i];
fprintf(g,"%lld",s*2+1);
    fclose(g);
    return 0;
}