View Code of Problem 71

#include<iostream>
#include<algorithm>
#include<math.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<cstring>
#include<string>
using namespace std;
int main() {
    double x=2,y=1,c,sum=0;
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
    {
    	sum+=x/y;
    	c=y;
    	y=x;
    	x=x+c;
	}
	printf("%.2lf",sum);
	return 0;
}