#include <bits/stdc++.h>
using namespace std;
const int NMAX=1e6;
int phi[NMAX+1];
int main(){
    int n, i, d;
    long long s;
    FILE *fin, *fout;
    fin=fopen("fractii.in", "r");
    fout=fopen("fractii.out", "w");
    fscanf(fin, "%d", &n);
    for(i=1; i<=n; i++)
        phi[i]=i;
    for(i=1; i<=n; i++)
        for(d=2*i; d<=n; d+=i)
            phi[d]-=phi[i];
    s=0;
    for(i=2; i<=n; i++)
        s+=phi[i];
    s=s*2+1; //punem si fractia 1/1
    fprintf(fout, "%lld", s);
    fclose(fin);
    fclose(fout);
    return 0;
}