View Code of Problem 71

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