#include <cstdio>
#define max_n 1000005 

using namespace std;

int n;
int sum[max_n];
long long sol;

void tera(){
    int i,j;
    for(i = 1;i<= n; i++)
    sum[i]=i-1;
    for(i = 2;i<=n;i++){
          for(j=(i<<1);j<=n;j+=i)
              //sum[j]=sum[j]-sum[i];
              sum[j]-=sum[i];
          sol+=sum[i];
    }
}

int main(void){
     freopen("fractii.in", "r", stdin);
     freopen("fractii.out", "w", stdout);
     scanf("%d ", &n);
     tera();
     sol*=2;sol+=1;
     printf("%d \n",sol);   
}