# include<iostream> # include<cstdio> # include<iomanip> using namespace std; int main(){ int n; double d1=1,d2=2,zhi=0,j=0; cin>>n; for(int i=1;i<=n;i++){ zhi+=d2/d1; j=d1; d1=d2; d2+=j; } cout<<zhi; return 0; }