#include<stdio.h>

int main()
{

freopen("fractii.in","r",stdin);

freopen("fractii.out","w",stdout);
long long N,j,phi[1000001],i,s;
scanf("%lld",&N);

for (i = 1; i <= N; ++i)
    phi[i] = i-1;

for (i = 2; i <= N; ++i)
    for (j = 2*i; j <= N; j += i)
	phi[j] -= phi[i];;
s=0;
for(i=2;i<=N;i++)
  s=s+phi[i];

printf("%lld",(2*s)+1);

return 0;
}