#include <cstdio>
#include <cmath>

using namespace std;

int v[1000100];

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