#include<cstdio>
#define NMAX 1000005
#define FIN "fractii.in"
#define FOUT "fractii.out"
using namespace std;
int f[NMAX],n;
long long rez=0;
int main()
{freopen(FIN,"r",stdin);
freopen(FOUT,"w",stdout);
scanf("%d",&n);
for(int i=1;i<=n;i++)
 f[i]=i-1;
for(int i=2;i<=n;i++)
 for(int j=2*i;j<=n;j+=i)
  f[j]=f[j]-f[i];
for(int i=2;i<=n;i++)
 rez+=f[i];
printf("%lld",2*rez+1);     
 
    
    return 0;}