View Code of Problem 71

#include<iostream>
using namespace std;
int main(void){
	double a[1000];
	double b=2,c=1,sum=0;
	for(int i=0;i<1000;i++){
		a[i]=b/c;
		b=b+c;
		c=b-c;
	}
	int n;
	cin>>n;
	for(int i=0;i<n;i++){
		sum+=a[i];
	}
	printf("%.2lf",sum);
}