PROGRAMMING:Grade conversion
It is required to output grades of "a", "B", "C", "d" and "e".
90 or above is "a", 80-89 is "B", 70-79 is "C", 60-69 is "d",
The score below 60 is "e".
###Input format:
There are several groups of test data, which are processed to the end of the file. Each group input a percentage score n, n is the integer number (0 < = n < = 100).
###Output format:
Each group outputs the characters corresponding to the score n of the Centennial system.
###Input example:
Here is a set of inputs. For example:
```in
eighty-six
ninety-eight
fifty-seven
sixty-three
```
###Output example:
The corresponding output is given here. For example:
```out
B
A
E
D
```
answer：If there is no answer, please comment
90 or above is "a", 80-89 is "B", 70-79 is "C", 60-69 is "d",
The score below 60 is "e".
###Input format:
There are several groups of test data, which are processed to the end of the file. Each group input a percentage score n, n is the integer number (0 < = n < = 100).
###Output format:
Each group outputs the characters corresponding to the score n of the Centennial system.
###Input example:
Here is a set of inputs. For example:
```in
eighty-six
ninety-eight
fifty-seven
sixty-three
```
###Output example:
The corresponding output is given here. For example:
```out
B
A
E
D
```
answer：If there is no answer, please comment