#include<stdio.h>

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

long long R;
int i,j,pr[1000005],N;

int main () {

	fscanf(f,"%d",&N);
	for ( i = 1 ; i <= N ; ++i )
		pr[i] = i - 1;
	
	for ( i = 2 ; i <= N ; ++i ){
		R += pr[i];
		for ( j = i + i ; j <= N ; j += i )
			pr[j] -= pr[i];
	}
	R = R + R + 1;
	
	fprintf(g,"%lld\n",R);
	
	fclose(f);
	fclose(g);
	
	return 0;
}