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

int prim(int x)
{
	int i;
	if(x == 1)
		return 0;
	for(i = 2;i <= x / 2;i++)
		if(x % i == 0)
			return 0;
	return 1;
}



int main()
{

	FILE *file;
	int n,i,nr;

	file = fopen("fractii.in","r");

	fscanf(file,"%d",&n);

	fclose(file);

	nr = n * n;
	nr -= n;
	nr++;

	for(i = 2;i <= n;i++)
	{
		if(n / i != 1 && prim(i) == 1)
		{
			nr -= (n / i - 1) * n / i;		
		}
	}

	file = fopen("fractii.out","w");
	fprintf(file,"%d",nr);
	fclose(file);

}