#include <bits/stdc++.h>

using namespace std;
int v[1001];
/*unsigned long long euler(int n)
{
    unsigned long long p,a,copie,i;
    p=n;
    copie=n;

    if(n%2==0)
    {
        p=p/2;
        while(n%2==0) n=n/2;
    }
    for(i=3; i*i<=n; i+=2)
    {
        if(n%i==0)
        {
            p=p/i;
            p*=(i-1);
            while(n%i==0) n=n/i;

        }
    }
    if(n>1)
    {
        p=p/n;
        p*=(n-1);
    }
    return p;
}
*/

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