#include<fstream.h>
long x,i,N,a[10000];
long long s;
int main()
{
ifstream f("fractii.in");
ofstream d("fractii.out");
f>>N;
for (i=1;i<=N;i++)a[i]=i-1;
s=0;
for (i=2;i<=N;i++)
{
x=2*i;
while (x<=N)
{
a[x]=a[x]-a[i];
x=x+i;
}
s=s+a[i];
}
s=2*s+1;
d<<s;
return 0;
f.close();
d.close();
}