#include <stdio.h>
#include <stdlib.h>
#define NMax 1000000
using namespace std;
FILE *fin,*fout;
int N,phi[NMax+1];
long long k=0;
int main()
{
    fin=fopen("fractii.in","r");
    fout=fopen("fractii.out","w");
    fscanf(fin,"%d",&N);
    for (int i = 1; i <= N; ++i)
    phi[i] = i-1;
    for (int i = 2; i <= N; ++i)
    for (int j = 2*i; j <= N; j += i)
        phi[j]=phi[j]-phi[i];
    for(int i=1;i<=N;i++)
        k+=phi[i];
    fprintf(fout,"%lld",2*k+1);
    return 0;
}