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