#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define mem(x,y) memset(x,y,sizeof(x))
const int M=2e5+10;
const int inf=1<<30;
const ll mod=1e9+7;
const int bit=32;
const double pi=acos(-1.0);
double dp[M];
int main(){
	int n;
	scanf("%d",&n);
	dp[n]=0;
	for(int i=n-1;i>=1;i--){
		dp[i]=dp[i+1]+1.0*n/(n-i);
	}
	printf("%.10lf\n",dp[1]);
	return 0;
}

#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
	cin.tie(nullptr)->sync_with_stdio(false);
	string s;
	cin >> s;
	string t = "ZONe"; 
	int ans = 0;
	for(int i = 0; i<9; i++){
		if(s.substr(i,4)==t)ans++;
	}
	cout << ans << "\n";
	return 0;
}