#include <cstdio>
#include <algorithm>
using namespace std;

#define MAX 8000000
#define ll long long
ll v[MAX];
int n, d;
void euler()
{
    int i, j, lim=MAX/8;
    for(i=1; i<=lim; i++) v[i] = i;
    for(i=2; i<=lim; i++){
        if(v[i]==i)
            for(j=i; j<=lim; j=j+i)
                v[j] -= v[j]/i;
        v[i] += v[i-1];
    }
}
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d%d",&n);
    euler();
    if(n<MAX)
        printf("%lld", v[n]*2-1);

}