View Code of Problem 48

#include<iostream>
#include<cstring>
using namespace std;
int main(){
	double sum = 0,up = 1,down = 1,t;
	int n;
	scanf("%d",&n);
	for(int i = 0;i<n;i++){
		t = down;
		down = up;
		up = up + t;
		sum = sum + up / down;
	}
	printf("%.6lf",sum);
	return 0;
}