Free all codes

#include < stdio.h >
void main()
{
  int marks;
  printf("Enter your marks : ");
  scanf("%d",&marks);

  if(marks>100)
/*marks greater than 100*/
    printf("Not valid marks");

  else if(marks>=80)
/*marks between 80 & 99*/
    printf("your grade is A");

  else if(marks >=70)
/*marks between 70 & 79*/
    printf("your grade is B");

  else if(marks>=50)
/*marks between 50 & 69*/
    printf("your grade is C");

  else if(marks>=35)
/*marks between 35 & 49*/
    printf("your grade is D");

  else
/*marks less than 35*/
    printf("your grade is E");
}