#include <stdio.h>
#include <stdlib.h>
int v[1000000];
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    long long n,i,j,s=0;
    scanf("%llu",&n);
    for(i=2;i<=n;i++)
    {
        v[i]=i-1;
    }
    for(i=2;i<=n;i++)
    {
        for(j=i+i;j<=n;j=j+i)
        {
            v[j]=v[j]-v[i];
        }
    }
    for(i=1;i<=n;i++)
    {
        s=s+v[i];
    }
    printf("%llu",s*2+1);
    return 0;
}