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