C :

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

C++ :

#include <iostream> 
#include <cstdio>
using namespace std;
int main()
{
	int n,p,q,t;
	double ans;
	p=1;
	q=2;
	ans=(double)q/p;
	cin>>n;
	for(int i=2;i<=n;i++)
	{
		t=p+q;
		p=q;
		q=t;
		ans=ans+(double)q/p;
	}
	printf("%.2lf\n",ans);
	return 0;
}