#include<cstdio>
using namespace std;
int i,j,n,v[1000000];
float s=0;
FILE *f1,*f2;
int main()
{
    f1=freopen("fractii.in","r",stdin);
    scanf("%d",&n);
    fclose(f1);
    v[0]=v[1]=0;
    for(i=2;i<=n;i=i+1)
    v[i]=i-1;
    for(i=2;i<=n-i;i++)
    {
    for(j=2*i;j<=n;j=j+i)
    v[j]=v[j]-v[i];
    }
    for(i=2;i<=n;i++)
    s=s+v[i];
    if(n==0)
    s=0;
    else
    s=2*s+1;
    f2=freopen("fractii.out","w",stdout);
    printf("%.0f\n",s);
    fclose(f2);
    return 0;
}