#include<bits/stdc++.h>//wa 45pts
using namespace std;
int n;
double x[100005],y[100005];//好好好 
double ans=1;
int main()
{
	cin>>n;
	x[1]=x[0]=1;
	for(int i = 2; i <= n+3; i++)
	{
		x[i]=x[i-1]+x[i-2];
	}
	for(int i = 2; i <= n; i++)
	{
		y[i]=x[i+2]-2;
	}
	for(int i = 2; i <= min(n,1300); i++)
	{
		ans+=1.00*x[i]/y[i];
		cout<<x[i]<<" "<<y[i]<<endl;
	}
	printf("%.3lf",ans);
	return 0;
}

如果去掉 min 结果会成为nan