#include<stdio.h>
long long rez[1000003],sol,n,i,d;
char ciur[1000003];
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%lld",&n);

    for(i=2;i<=n;i++)
        rez[i]=i-1;
    for(i=2;i<=n;i++)
    {
      
        for(int j=2*i;j<=n;j+=i)
            rez[j]-=rez[i];
        sol+=rez[i];
     }

    printf("%lld",sol*2+1);
    return 0;
}