#include<cstdio>
#define nmax 1000010
using namespace std;
int n,i,j,v[nmax],nr;
long long sol;
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d", &n);
    for(i=2;i<=n;++i)v[i]=i-1;
    for(i=2;i<=n;++i)
        for(j=i+i;j<=n;j+=i)
            v[j]-=v[i];
    for(i=n;i>1;--i)
        sol=(long long)(sol+v[i]);
    printf("%lld", 2*sol+1);
    return 0;
}