#include<stdio.h>
#include<iostream>
using namespace std;
unsigned long long phi[10000000];
int main()
{
    unsigned long long n,nr=0,i,j;
    
    FILE *in = fopen("fractii.in", "r");
    FILE *out = fopen("fractii.out", "w");
    fscanf(in, "%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];
                    
            nr += (2 * phi[i]) - 1;

    }

    nr +=  n ;

    fprintf(out,"%lld", nr);
    
    
}