#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ll n, ans = 0;
    cin >> n;
    for(ll i = 1; i * i <= n; i++){
        ll L = n / i;
        ll R = n / (i + 1);
        if(n % L == 0) L--;
        //if(n % R == 0) R++;
        ans += L - R;
    }
    cout << ans << '\n';
}