#include <cstdio>
#include <cmath>

long long n,max,sq,d=-1,phi[1000001];

long long euler() {
	long long rezultat=0;
	for (int i = 1; i <= n; ++i)
    	phi[i] = i-1;
	for (int i = 2; i <= n; ++i) {
		rezultat+=phi[i];//numarul de fractii subunitare
    	for (int j = 2*i; j <= n; j += i)
        	phi[j] -= phi[i];
	}
	return 2*rezultat+1;
}

int main()
{
	FILE *f=fopen("fractii.in","r");
	FILE *g=fopen("fractii.out","w");
	fscanf(f,"%d",&n);
	sq=sqrt((double)n);
	fprintf(g,"%lld",euler());
	fclose(f);
	fclose(g);
	return 0;
}