#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;      
}