FZU1058

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<vector>
#include<queue>
#include<iostream>
#include<iomanip>
#include<algorithm>
using namespace std;
typedef long long LL;
typedef long double LDB;

int main(){
    int n;
    while(~scanf("%d",&n)){
        LDB ans=0;
        for(int i=1;i<=n;i++){
            ans+=(LDB)1/i;
        }
        cout<<fixed<<setprecision(12)<<ans<<endl;
    }
    return 0;
}