#include<bits/stdc++.h> using namespace std; int main() { double n, sum = 0, jc; cin >> n; for(int i=1;i<=n;i++){ jc = 1; for(int j=1;j<=i;j++){ jc*=j; } sum+=1/jc; } cout <<fixed<<setprecision(10)<< sum; return 0; }