#include <fstream>

using namespace std;

FILE *fin=fopen("fractii.in","r");
FILE *fout=fopen("fractii.out","w");

int n,i,j,euler[1000010];
long long int s;
int main()
{
    fscanf(fin,"%d",&n);
    for(i=1;i<=n;i++)
        euler[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=i*2;j<=n;j+=i)
            euler[j]-=euler[i];
    for(i=1;i<=n;i++)
        s+=euler[i];
        s=s*2+1;
    fprintf(fout,"%lld",s);
    return 0;
}