C :

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
  double a=2,b=1;
  int m,i;
  double sum=2;
  scanf("%d",&m);
  for(i=2;i<=m;i++)
  {
        int k;
        k=b;
        b=a;
        a+=k;
        sum+=a/b;
  }
  printf("%.2lf",sum);

  return 0;
}

C++ :

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