#include <iostream> //designed by hu 2025-10 using namespace std; int main(){ int a1=2,a2=3,a,b1=1,b2=2,b; int n; cin>>n; double res=a1/(double)b1; for(int i=2;i<=n;i++){ res = res + a2/(double)b2; a = a1+a2; a1=a2; a2=a; b = b1+b2; b1=b2; b2= b; } cout<< res; return 0; }