#include<stdio.h>
#include<math.h>

long long sum=0;
long v[1000001L][11], n, pows[20];
int vc[1000001L];
char vnotprime[1000001L],vsquare[1000001L];

int doit()
{
	long i,j,k,l,s;
    long long p,d;
	
	//genereaza puterile lui 2
	pows[0]=1;
    i=0;
	while(pows[i]<n)
	{
        i++;
        pows[i]=pows[i-1]*2;
    }
	
	//genereaza numerele prime
	for(i=2;i<=n;i++)
	{
		s=long(sqrt(i));
		if(vnotprime[i]==0)
		{
            v[i][0]=i;
            vc[i]++;
        }
        else
        {
    		if(s*s==i)//daca este patrat perfect
    		{
    			vsquare[i]=1;
    		}
        }
		s=i+i;
		while(s<=n)//ex.: i=2; luam 4, 6, 8, 10...
		{
			if(vnotprime[i]==0)//daca nu are niciun divizor patrat perfect
			{
				v[s][vc[s]]=i;
				vc[s]++;
			}
			vsquare[s]=vsquare[i];
			vnotprime[s]=1; //numarul nu e prim
			s+=i;
		}
	}
	sum=n;
	for(i=2;i<=n;i++)
	{
		//printf("\n%ld) ",i);
        sum+=n;
        //s=0;
        for(j=0;j<vc[i];j++)
        {
            //printf("-%ld ",v[i][j]);
            //s-=(n/v[i][j]);
            sum-=(n/v[i][j]);
        }
        if(vc[i]>1)
        {
            for(k=0;k<vc[i];k++)
            {
				d=k+1;
                for(l=d;l<vc[i];l++)
                {
	                //printf("+%ld ",v[i][k]*v[i][l]);
	                sum+=(n/(v[i][k]*v[i][l]));	
	                //s+=(n/(v[i][k]*v[i][l]));	
                }
            }
        }
        //printf("[%lld]",-s);
    }
    //sum++;
    
	return 0;		
}

int main()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	
	scanf("%ld",&n);	
	doit();
	printf("%Ld",sum);
/*
	long i,j;
	for(i=2;i<=n;i++)
	{
		printf("\n%ld -> ",i);	
		for(j=0;j<vc[i];j++)
		{
			printf("%ld, ",v[i][j]);
		}	
	}*/
	
	fclose(stdin);
	fclose(stdout);
	return 0;
}