#include <stdio.h>
#include <math.h>
FILE *f;
long long n;   
int main(void){
	long long a[100000000],i,j,c;
	f=fopen("fractii.in","r");
	fscanf(f,"%lld",&n);
	fclose(f);
	for (i=1;i<=n;i++){
		a[i]=i-1;
	}
	
	for(i=2;i<=n;i++){
		for(j=i+i;j<=n;j=j+i){
			a[j]-=a[i];
		}
		c+=a[i];
	}
	f=fopen("fractii.out","w");
	fprintf(f,"%lld",c*2+1);
	fclose(f);
}