#include<stdio.h>
int f[1000001],n;
long nrf;
int main ()
{
    int i,j;
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++)
        f[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=2*i;j<=n;j=j+i)
            f[j]=f[j]-f[i];
    for(i=2;i<=n;i++)
        nrf=nrf+f[i];
    printf("%ld",2*nrf+1);
    return 0;
}