#include <stdio.h>

// numarul de fractii ireductibile;

int main()
{
    long int n,j,i;
    freopen ("fractii.in", "r", stdin);
    freopen ("fractii.out", "w", stdout);

    scanf ("%ld", &n);
    long int a[n];
    long long s = 0;

    for (j = 1; j <= n; j++)
	    a[j] = j - 1;	
    for (i = 2; i <=(n+1)/2; i ++)
	    for (j = 2*i;j <= n;j +=i)
	        a[j] -= a[i];

    for (i = 1; i <= n; i++)
	    s = s + a[i];
    printf ("%lld", s*2 + 1);
    return 0;
}