View Code of Problem 71

#include<iostream>
#include<cstdio>

using namespace std;

int main()
{
  int n;
  cin>>n;
  int a=2,b=1;double sum=0;
  while(n--)
  {
    sum=(a*1.0/b)+sum;
    int temp=a;
    a=a+b;
    b=temp;
  }
  printf("%.2f",sum);
}