View Code of Problem 71

#include <stdio.h>
int main(){
	int n;
	double sum=0.0,a=2,b=1,c;
	scanf("%d",&n);
	for(int i=1;i<=n; i++)
	{
		sum += a/b;
		c=a;
		a=a+b;
		b=c;
	}
	printf("%0.2lf",sum);
	return 0;
}