#include <cstdio>
int main (){
	freopen("fractii.in","rt",stdin);
	freopen("fractii.out","wt",stdout);
    	
    	long n,i,j;
    	unsigned long long s=0;
	
	scanf("%d",&n);
	
	int t[1000000];
    
    	for(i=1;i<=n;++i)
    		t[i]=i-1;
    	for(i=2;i<=n;++i)
    		for(j=2*i;j<=n;j+=i)
    			t[j]-=t[i];
    	for(i=2;i<=n;i++)
    		s+=t[i];
    	printf("%lld",s*2+1);
    	return 0;
}