#include <stdio.h>


long cmmdc(long a,long b)
{
	while(a!=b)
	{
		if(a>b)
			a=a-b;
		else
			b=b-a;
	}
	return a;
}

long int div(long int x)
{
	long int nr=0;
	int i;
	for(i=2;i<=x;i++)
		if(cmmdc(x,i)!=1)
			nr++;

	return nr;
}

int main(void)
{
	long int n,j,prec;
	FILE *fin;
	fin = fopen("fractii.in","r");
	fscanf(fin,"%d",&n);
	fclose(fin);
	j=1;
	while(j<=n)
	{
		if(j==1)
			prec=1;
		else
		{
			prec=prec+2*(j-div(j));
		}
		j++;
	}
	fin=fopen("fractii.out","w");
	fprintf(fin,"%d",prec);
	fclose(fin);
	return 0;
}