# include<iostream> # include<cstdio> using namespace std; int main() { float sum=0,fm=1,fz=2,n,fm0,fz0; cin>>n; for(int i=1;i<=n;i++){ sum+=fz/fm; fm0=fm; fz0=fz; fz=fz0+fm0; fm=fz0; } printf("%.4f",sum); return 0; }