#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main ()
{FILE *f,*g;
f=fopen("fractii.in","rt");
g=fopen("fractii.out","wt");
int n,i,j,*v;
unsigned long long k=0;
fscanf(f,"%i",&n);
v=(int*)malloc((n+1)*sizeof(int));

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]=round(v[j]*(1-(float)1/i));
for (i=1; i<=n; i++)
    k+=v[i];

   
fprintf(g,"%lld",k*2-1);
fclose(f);
fclose(g);
return 0;}