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