#include <cstdio>

using namespace std;

long long p[1000005], n, sum;

void calc()
{
    for(long long i=2; i<=n; i++)
    {
        for(long long j=i+i; j<=n; j+=i)
        {
            p[j]-=p[i];
        }
        sum+=p[i];
    }
}

int main()
{

    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);

    scanf("%lld", &n);
    p[1]=1;
    for(long long i=2; i<=n; i++)
        p[i]=i-1;
    calc();
    printf("%lld", 2*sum+1);
    return 0;
}