#include <cstdio>
int p[1000005],n;
long long sum;
int main(){
    int i,j;
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for(i = 1;i<=n;i++) p[i]=i;
    for(i=1;i<=n;i++)
    {
        sum+=p[i];
         for(j = 2; i*j<=n;j++)
          p[i*j]-=p[i];
    }
    printf("%lld",2*sum-1);
    return 0;
}