//fractii. 
#include<iostream.h>
long p,q,i,j,ok=0,n,k,r,a[1000000];
//functia phi calculeaza numarul de numere prime cu n mai mici ca n
long phi(long x)
{
	for(i=1;i<=x;i++)
	{
		p=x;
		q=i;
		while(q)
		{
			r=p%q;
			p=q;
			q=r;
		}
		if(p==1)
			k++;
	}
	return k;
}
int main()
{
	cout<<"dati n: "; cin>>n;
/*	for (i=1;i<n+1;i++)
		phi[i] =i-1;
	for (i=2;i<n+1;i++)
		for (j=2*i;j<=n;j+=i)
		{
			phi[j]-=phi[i];
			cout<<phi[j]<<" ";
		}*/
	for(long j=1;j<=n;j++)
		a[j]=phi(j);
		//cout<<phi(j)<<" ";
	cout<<2*a[n]-1<<" ";
return 0;
}