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#include <iostream>
#include <fstream>

using namespace std;
int f(int i);

int main()
{
    int n,i;
    long long int s=1;
    ifstream fin ("fractii.in");
    fin >>n;
    fin.close();
    for (i=2;i<=n;i++)
        s+=2*(i-f(i)-1);
    ofstream fout ("fractii.out");
    fout <<s;
    fout.close();
    return 0;
}

int f(int i)
{
    int k,nr=0,ii=i;
    for (k=2;k<=ii;k++)
        if(i%k==0)
        {
            nr+=i/k-1;
            do{
                ii/=k;
            }while(ii%k==0);
        }
    return nr;
}