useer = int(input("Enter number ples :"))
if useer >= 101:
print("The grade is wrong range between 0 to 100 ?")
if 90 <= useer <=100:
print("A")
elif useer >=80 and useer <=89:
print("B")
elif useer >=70 and useer <=79:
print("C")
elif useer >= 60 and useer <=69:
print("D")
elif useer >= 50 and useer <= 59:
print("E")
elif useer <=49 and useer >=0:
print("F-")
elif useer <= -1:
print("erore")