#include<iostream> #include<iomanip> using namespace std; int main() { double fz=2,fm=1,s=fz/fm,t; int n,i; cin>>n; for(i=2;i<=n;i+=1){ t=fm; fm=fz; fz=t+fz; s+=fz/fm; } printf("%.4lf",s); return 0; }