Viral Advertising Hackerrank solution in c

#include<stdio.h>

#include<stdlib.h>

#include<assert.h>

#include<math.h>

int main()

{

int n;

scanf("%d",&n);

int sum,k,d=0;

int p=5;

for(int i=1;i<=n;i++)

{

d=p;

k=d/2;

p=k*3;

sum=sum+k;

}

printf("%d",sum);

return 0;

}