def grades2 (): 
     gpa = input ("Enter the grade point: ")
     if (gpa == 4):
         letter = 'A'

     elif (gpa == 3):
         letter = 'B'

     elif (gpa == 2):
         letter = 'C';

     elif (gpa == 1):
         letter = 'D'

     elif (gpa == 0):
          letter = 'F'

     else:
          print "GPA must be one of '4', '3', '2', '1' or '1'"
          letter = 'NA'
     print gpa, letter