#include <stdio.h>
FILE *fin, *fout;
int main()
{
	fin = fopen("fractii.in", "r");
	fout = fopen("fractii.out", "w");
	int n;
	fscanf(fin, "%d", &n);
	long long int  sum = 0;
	int sieve[n+23];
	for(int i = 1; i<= n; i++) sieve[i] = i-1;
	for(int i = 2; i<= n; i++)
	{
		for(int j = 2*i; j<= n; j+=i)
		{
			sieve[j] -= sieve[i];
		}
		sum+= sieve[i];
	}
	fprintf(fout, "%lld\n", sum * 2 + 1);
	fclose(fin);
	fclose(fout);
	return 0;
}