Grading Students(Hacker Rank)

vector<int> gradingStudents(vector<int> grades)

 {

     int length = grades.size();

     for(int i=0;i<length;i++)

     {

         int a = grades[i];

       

         int div = a/5;

         div++;

         if(((div*5) - a) <3)

         {

             if(div*5>=40)

             grades[i]=div*5;

         }

       

     }

     return grades;

}