#include<iostream> #include<cstdio> //scanf()\printf() #include<cstring> #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int z=2,m=1,n,t; double sum=z*1.0/m; cin>>n; for(int i=2;i<=n;i++){ t=m; m=z; z+=t; sum+=z*1.0/m; } cout<<sum; return 0; }