#include <cstdio>
#include "stdlib.h"

int main()
{
	int *phi;
	FILE *f = fopen("fractii.in","r");
	FILE *g = fopen("fractii.out","w");

	int n;
	fscanf(f,"%d",&n);

	phi = (int*)malloc((1+n)*sizeof(int));
	int s = 1;

	//compute phi(n)
	for (int i=1;i<=n;i++) phi[i]=i;

	for (int i=2;i<=n;i++)
	{
		if (phi[i]==i)
			 for (int j=i;j<=n;j+=i)
				 {
					 phi[j] /=i;
					 phi[j] *= (i-1);
			 }
		s += phi[i];
	}

	fprintf(g,"%ld",s);

	fclose(f);
	fclose(g);
}