#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    ll n;
    cin >> n;
    vector<ll> cnt(n+1);
    for(int i=n;i>=2;i--){
        ll a = n/i;
        ll tmp = a*a;
        tmp -= n/i;
        tmp/=2;
        for(int j=i;j<=n;j+=i){
            tmp -= cnt[j];
        }   
        cnt[i] = tmp;
    }
    ll ans = accumulate(cnt.begin(),cnt.end(),0ll);
    dbg(ans);
    for(int i=2;i<=n-1;i++){
        ans -= n/i - 1;
    }
    cout << ans << endl;
    return 0;
}