#### Viral Advertising

HackerLand Enterprise is adopting a new viral advertising strategy. When they launch a new product, they advertise it to exactly 5 people on social media.

On the first day, half of those 5 people (i.e.,floor(5/2)=2 ) like the advertisement and each person shares it with 3 of their friends; the remaining people (i.e.,5-floor(5/2)=3) delete the advertisement because it doesn’t interest them. So, at the beginning of the second day,floor(5/2) X 3=2 X 3=6 people receive the advertisement.

On the second day, half of the 6 people who received the advertisement share it with 3 new friends. So, at the beginning of the third day, floor(6/2) X 3=3 X 3=9 people receive the advertisement. The diagram below depicts the advertisement’s virality over the first three days (green denotes a person that likes the advertisement and red denotes a person that disliked and deleted it):

Assume that at the beginning of the ith day, people received the advertisement, floor(m/2) people like and share it with 3 new friends, and m-floor(m/2) people dislike and delete it. At the beginning of the (i+1)th day, floor(m/2)X3 people receive the advertisement.

Given an integer, n, find and print the total number of people who liked HackerLand Enterprise’s advertisement during the first n days. It is guaranteed that no two people have any friends in common and, after a person shares the advertisement with a friend, the friend always sees it the next day.

Input Format

A single integer, n, denoting a number of days.

Constraints

1<=n<=50
Output Format
Print the number of people who liked the advertisement during the first days.
Sample Input
3
Sample Output
9
Explanation
This example is depicted by the diagram at the top of the challenge. people liked the advertisement on the first 2day, 3 people liked the advertisement on the second day and 4 people liked the advertisement on the third day, so the answer is 2+3+4=9.

##### I method

#include <cmath> #include <cstdio> #include <vector> #include <iostream> #include <algorithm> using namespace std; int main() { int n,like,a,v; cin>>n; v=6; a=0; like=2; for(int i =2;i<=n;i++) { a=floor(v/2); like+=a; v=(a)*3; } cout<<like<<endl; return 0; }

##### II Method

```
n = int(input())
shared = 5
total_opened = 0
for _ in range(0, n):
opened = int(shared / 2)
total_opened = total_opened + opened
shared = opened * 3
print(total_opened)
```