m= int(input("enter the marks= "))
if(m>=80):
    print("grade is A")
elif(m>=60 and m<80):
    print("grade is B")
elif(m>=50 and m<60):
    print("The grade is C")
elif(m>=45 and m<50):
    print("The grade is D")
elif(m>=25 and m<45):
    print("The grade is E")
else:
    print("The grade is F")
