#include<cstdio>
int v[1000001];
int main(){
    int n,i,j;
    long long s;
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for(i=1;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];
    s=1;
    for(i=1;i<=n;i++)
        s+=2*v[i];
    printf("%lld",s);
    return 0;
}