View Code of Problem 48

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<vector>
#include<map>
#include<string>
#include<set>
using namespace std;
int main(void){
	int n;
	while(cin>>n) {
		double sum=0;
		double a=2,b=1;
		for(int i=0;i<n;i++) {
			sum+=a/b;
			int flag=a;
			a+=b;
			b = flag;
		}
		printf("%.6lf\n",sum);
	}
	
}