#include <stdio.h>  
 long long n,i,j,a[1000002];  
 int main()  
 {  
     freopen("fractii.in","r",stdin);  
     freopen("fractii.out","w",stdout);  
     scanf("%lld",&n);  
     for (i=1; i<=n; ++i) a[i]=i-1;  
     for (i=2; i<=n; ++i)  
         for (j=i*2; j<=n; j+=i) a[j]-=a[i];  
     for (i=0, j=0; i<=n; ++i, j+=a[i]);  
     printf("%lld",j*2+1);  
     return 0;  
 }