#include<cstdio>
#define MAX_N 1000000
using namespace std;

int phi[MAX_N+1], n;

int main()
{
    int i, j;
    long long result;
    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 - 1;
    for(i=2; i<=n; i++)
        for(j=2*i; j<=n; j+=i)
            phi[j] -= phi[i];

    phi[1] = 1;
    result = 0;
    for(i=1; i<=n; i++)
        result += phi[i];
    fprintf(fout,"%lld\n",2*result-1);
    fclose(fin);
    fclose(fout);
    return 0;
}