#include <bits/stdc++.h>/*
#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")*/
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define all(a) a.begin(),a.end()
#define rsort(a) {sort(all(a));reverse(all(a));}
#define pb emplace_back
#define eb emplace_back
#define lb(v,k) (lower_bound(all(v),(k))-v.begin())
#define ub(v,k) (upper_bound(all(v),(k))-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
#define dupli(a) {sort(all(a));a.erase(unique(all(a)),a.end());}
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
typedef multiset<ll> S;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vvvvi=vector<vvvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001001;
const ll INF=1001001001;
const ll mod=1000000007;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void noyes(T b){if(b)out("no");else out("yes");}
template<class T> void NoYes(T b){if(b)out("No");else out("Yes");}
template<class T> void NOYES(T b){if(b)out("NO");else out("YES");}
void outs(ll a,ll b){if(a>=inf-100)out(b);else out(a);}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll modpow(ll a,ll b){ll res=1;a%=mod;while(b){if(b&1)res=res*a%mod;a=a*a%mod;b>>=1;}return res;}
inline ll readll() {
    ll x = 0;
    char ch = getchar_unlocked();
    while (ch < '0' || ch > '9') ch = getchar_unlocked();
    while (ch >= '0' && ch <= '9'){
		x = (x << 3) + (x << 1) + ch - '0';
		ch = getchar_unlocked();
	}
    return x;
}
class segtree{
    vi seg;ll N=1;
public:
    ll g=0;
    ll f(ll a,ll b){
        return a+b;
    }
    segtree(ll n,ll k){
        while(N<n)N*=2;
        seg=vi(N*2-1,g);
        rep(i,n)seg[i+N-1]=k;
        for(ll i=N-2;i>=0;i--)seg[i]=f(seg[i*2+1],seg[i*2+2]);
    }
    segtree(vi v){
        while(N<v.size())N*=2;
        seg=vi(N*2-1,g);
        rep(i,v.size())seg[i+N-1]=v[i];
        for(ll i=N-2;i>=0;i--)seg[i]=f(seg[i*2+1],seg[i*2+2]);
    }
    void change(ll i){
        i+=N-1;
        seg[i]=1-seg[i];
        while(i>0){
            i=(i-1)/2;
            seg[i]=f(seg[i*2+1],seg[i*2+2]);
        }
    }
    ll get(ll a,ll b,ll k=0,ll l=0,ll r=-1){
        if(r==-1)r=N;
        if(a<=l&&r<=b)return seg[k];
        if(r<=a||b<=l)return g;
        return f(get(a,b,k*2+1,l,(l+r)/2),get(a,b,k*2+2,(l+r)/2,r));
    }
    void debug(ll n){
        rep(i,n)cout<<' '<<seg[i+N-1];cout<<endl;
    }
};
double mpow(double a,ll b){
    if(b==0)return 1;
    if(b&1)return a*mpow(a,b-1);
    double k=mpow(a,b/2);
    return k*k;
}
int main(){
    decimal;
    ll n;cin>>n;
    double ans=0;
    vector<double> t(50000);
    rep(i,50000)t[i]=1/mpow(i+1,n);
    // outv(t);
    REP(a,1,10000)REP(b,a+1,20000)ans+=(t[a-1]-t[b-1])/b/(b-a);
    out(ans);
}