#include<bits/stdc++.h>
//#include <atcoder/all>

#define rep(i,n)for(int i=0;(i)<(int)(n);i++)
#define REP(i,a,b)for(int i=(int)(a);(i)<=(int)(b);i++)
#define ALL(a)  (a).begin(),(a).end()
#define pb push_back
#define fi first
#define se second
#define sz(x) ((int)x.size())
 
using namespace std;
//using namespace atcoder;
using ld = long double;
using ll = long long;
using P = pair<ll, ll>;
 
template<typename T> bool chmin(T& a, const T& b) { if(a > b){ a = b; return 1;} return 0; }
template<typename T> bool chmax(T& a, const T& b) { if(a < b){ a = b; return 1;} return 0; }

const ll ZER = 0;
const ll MOD = 998244353;
const ll INF = 1e9;



int main(){
    int n;
    cin >> n;
    double res = 0;
    REP(i, 1, n - 1){
      res += (double)1.0 / (double)i;
    }
    cout << fixed << setprecision(10) << (double) n * res<< endl;
}
#include<bits/stdc++.h>
#define rep(i,a,...) for(int i = (a)*(strlen(#__VA_ARGS__)!=0);i<(int)(strlen(#__VA_ARGS__)?__VA_ARGS__:(a));++i)
#define per(i,a,...) for(int i = (strlen(#__VA_ARGS__)?__VA_ARGS__:(a))-1;i>=(int)(strlen(#__VA_ARGS__)?(a):0);--i)
#define foreach(i, n) for(auto &i:(n))
#define all(x) (x).begin(), (x).end()
#define bit(x) (1ll << (x))
#define lambda(RES_TYPE, ...) (function<RES_TYPE(__VA_ARGS__)>)[&](__VA_ARGS__) -> RES_TYPE
#define method(FUNC_NAME, RES_TYPE, ...) function<RES_TYPE(__VA_ARGS__)> FUNC_NAME = lambda(RES_TYPE, __VA_ARGS__)
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
//const ll MOD = (ll)1e9+7;
const ll MOD = 998244353;
const int INF = (ll)1e9+7;
const ll INFLL = (ll)1e18;
template<class t>
using vvector = vector<vector<t>>;
template<class t>
using vvvector = vector<vector<vector<t>>>;
template<class t>
using priority_queuer = priority_queue<t, vector<t>, greater<t>>;
template<class t, class u> bool chmax(t &a, u b){if(a<b){a=b;return true;}return false;}
template<class t, class u> bool chmin(t &a, u b){if(a>b){a=b;return true;}return false;}
#ifdef DEBUG
#define debug(x) cout<<"LINE "<<__LINE__<<": "<<#x<<" = "<<x<<endl;
#else
#define debug(x) (void)0
#endif

namespace templates{
  ll modpow(ll x, ll b,ll mod=MOD){
    ll res = 1;
    while(b){
      if(b&1)res = res * x % mod;
      x = x * x % mod;
      b>>=1;
    }
    return res;
  }

  ll modinv(ll x){
    return modpow(x, MOD-2);
  }

  bool was_output = false;
  template<class t>
  void output(t a){
    if(was_output)cout << " ";
    cout << a;
    was_output = true;
  }
  void outendl(){
    was_output = false;
    cout << endl;
  }
  ll in(){
    ll res;
    cin >> res;
    return res;
  }

  template<class t>
  istream& operator>>(istream&is, vector<t>&x){
    for(auto &i:x)is >> i;
    return is;
  }

  template<class t, class u>
  istream& operator>>(istream&is, pair<t, u>&x){
    is >> x.first >> x.second;
    return is;
  }

  template<class t>
  t in(){
    t res; cin >> res; return res;
  }

  template<class t>
  void out(t x){
    cout << x;
  }

  template<class t>
  vector<t> sorted(vector<t> line,function<bool(t,t)> comp=[](t a,t b){return a<b;}){
    sort(line.begin(),line.end(),comp);
    return line;
  }

  template<class t>
  vector<t> reversed(vector<t> line){
    reverse(line.begin(),line.end());
    return line;
  }
}

using namespace templates;

ll func(){
    ll n = in()*2;
    set<ll> s;
    for(ll i=1;i*i<=n;++i){
        if(n%i)continue;
        s.emplace(i);
        s.emplace(n/i);
    }
    ll ans = 0;
    foreach(i,s){
        if((i&1)==((n/i)&1))continue;
        ++ans;
    }
    return ans; 
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << func() << endl;
  return 0;
}
