#include<iostream>
#include<stdio.h>
using namespace std;
int phi[(int)1e6+1];
int n;
int main(){
    FILE *f = fopen("fractii.in","r");
    fscanf(f,"%d",&n);
    fclose(f);
    phi[1]=0;
    for(int i=2;i<=n;i++){
        phi[i]=i;
    }
    for(int i=2;i<=n;i++){
        if(phi[i] == i){
            for(int j=i;i<=n;j+=i){
                phi[j]=phi[j]/i*(i-1);
            }
        }
    }
    long long int s=0;
    FILE *g = fopen("fractii.out","w");
    for(int i=1;i<=n;i++){
        s+=phi[i];
    }
    fprintf(g,"%lld",s*2+1);
    fclose(g);
    return 0;
}