#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int n,fz=2,fm=1,t; double s=fz*1.0/fm; cin>>n; for(int i=2;i<=n;i++){ t=fm; fm=fz; fz=fz+t; s+=fz*1.0/fm; } cout<<s; return 0; }