#include <cstdio>

int a[1000002];
int i,j;
long long n, rez;

int main() {
	FILE *f,*g;
	f = fopen("fractii.in","r");
	g = fopen("fractii.out","w");
	fscanf(f,"%ld",&n);
	for (i = 2; i<=n; ++i) {
		a[i] = i-1;
	}
	for (i = 2; i<=n; ++i) {
		for (j = 2*i; j<=n; j+=i) {
			a[j] -= a[i];
		}
	}
	for (i = 2; i<=n; ++i) {
		rez += a[i];
	}
	rez *= 2;
	rez++;
	
	fprintf(g,"%lld",rez);
	
	fclose(f);
	fclose(g);
	return 0;
}