View Code of Problem 71

 //  2/1 3/2 5/3 8/5 13/8 21/13
#include<stdio.h>
int main()
{
	int n;
	scanf("%d",&n);
	double fenzi=1.0,fenmu=1.0,fenshu ,temp,sum=0;
	while(n!=0)
	{
		temp = fenzi;
		fenzi = fenmu + fenzi;
		fenmu = temp;
		fenshu = fenzi/fenmu;
		sum+=fenshu;
		n--;
	}
	printf("%.2f",sum);
	return 0;
}