View Code of Problem 48

#include<iostream>
#include<algorithm>
#include<math.h>
using namespace std;
int main() {
	double n,a=2.0,b=1.0,c;
	int num;
	cin>>num;
	for(int i=0;i<num;i++)
	{
		n+=a/b;
		c=b;
		b=a;
		a+=c;
	}
	printf("%.6lf",n);
	return 0;
}