#include <bits/stdc++.h>
#define ll long long
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
const int N = 1e6+5;
int prime[N], n;
int euler(int x){
    int ans = x;
    for(int p = 2; p*p <=x; p++){
        if(x % p == 0){
            while(x % p == 0) x/=p;
            ans -= ans / p;
        }
    }
    if(x > 1) ans -= ans/x;
    return ans;
}
int rez(int n){
    if(n == 1) return 1;
    if(n == 2) return 3;
    return 2*euler(n) + rez(n-1);
}
int main(){
    fin >> n;
    fout << rez(n);
    return 0;
}