#include <stdio.h>


void main(){
  int marks = 100;
  if (marks<0){printf("wrong input");}
  else if (marks <33){printf( "Grade is F");}
  else if (marks <40) {printf("Grade is D");}
  else if (marks<60)  {printf ("Grade is C");}
  else if  (marks<80) {printf ("Grade is B");}
  else if  (marks<=100) {printf (" Grade is A");}
  else {printf ("wrong input");}



  return 0;
}