View Code of Problem 71

#include <stdio.h>
 
 
int main()
{
 
	double fn1=1,fn2=2,fn;
	double sum=0,temp;
	int n;
	scanf("%d",&n);
	while(n--)
	{
		fn=fn2/fn1;
		temp=fn2;
		fn2=fn1+fn2;
		fn1=temp;
		sum+=fn;
	}
	
	
	
	printf("%.2f",sum);
 
	
}