#include <cstdio>
#define maxn 1<<20

int x[maxn], n;

int main()
{
	freopen("fractii.in", "r", stdin);
	scanf("%d\n", &n);
	int i, j;
	int nr=0;
	for(i=4;i<=n;i+=2) nr++;
	for(i=4;i<=n;i+=2) x[i]=nr;
	x[2]=nr+1;
	
	for(i=3;i<=n;i++)
	{
		nr=0;
		
		if(x[i]==0)
		{
			nr=0;
			for(j=i+i;j<=n;j+=i) nr++;
			for(j=i+i;j<=n;j+=i) x[j]+=nr;
			x[i]+=nr+1;
		}
		else
		{
			nr=0;
			for(j=i+i;j<=n;j+=i) if(x[j/i]==0) nr++;
			for(j=i+i;j<=n;j+=i) if(x[j/i]==0) x[j]+=nr;
			x[i]+=nr+1;
		}
	}
	
	long long sum=n;
	for(i=2;i<=n;i++) sum+=n-x[i];
	
	freopen("fractii.out", "w", stdout);
	printf("%lld\n", sum);
	return 0;
}