View Code of Problem 71

#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
	int n;
	cin>>n;
	double a=2;
	double b=1;
	double sum=0;
	while(n--)
	{
		sum=sum+a/b;
		a=a+b;
		b=a-b;
		
	}
	cout<<setiosflags(ios::fixed)<<setprecision(2)<<sum;
		
	return 0;
}