#include<stdio.h>

long n,i,nr,j,phi[1000001];

int main()
{

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

freopen("fractii.out","w",stdout);

scanf("%ld",&n);

nr=0;

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];
for(i=1;i<=n;i++)
  nr=nr+phi[i];

printf("%ld",nr*2+1);

return 0;
}