//fractii 
#include<stdio.h>
#include<stdlib.h>

int main(){
    long long int * phi, n, rez=0, i, j;
    FILE *f;
    
    f=fopen("fractii.in", "r");
	
    fscanf(f,"%lld",&n);
    phi=(long long int*)malloc(sizeof(long long int)*(n+1));  
    fclose(f);

    phi[1]=1;
    for(i=2;i<=n;i++)
       phi[i]=i;
    for(i=2;i<=n;i++){
       if(phi[i]==i){
          phi[i]=i-1;
          for(j=2*i;j<=n;j=j+i){
             phi[j]=phi[j]*(i-1)/i ;                  
          }              
       } 
       rez =  rez + phi[i];             
    } 
    rez =rez*2 ;
    rez=rez+1;
    f=fopen("fractii.out", "w");
    fprintf(f,"%lld",rez);
    fclose(f);	
}