View Code of Problem 48

#include<bits/stdc++.h>
using namespace std;



int main() {

	int n;
	cin>>n;
	double pre=1,now=2;
	double sum=0;
	for(int i=0;i<n;i++){
		sum+=now/pre;
		double k=now;
		now+=pre;
		pre=k;
	}
	printf("%.6lf",sum);
	return 0;
}