#include<cstdio>
using namespace std;
int i,v[1000001],j,n;
long long rez;
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=2*i;j<=n;j+=i)
              v[j]-=v[i];
         rez+=v[i];}
     rez=2*rez+1;
     printf("%lld",rez);

    return 0;
   }