PROGRAMMING:JMU Python grade conversion
This problem requires the preparation of a program to convert a hundred point score into a five point score. Conversion rules:
90 or more is a;
B is less than 90 and greater than or equal to 80;
C is less than 80 and greater than or equal to 70;
D is less than 70 and greater than or equal to 60;
Less than 60 is e.
###Input example:
```in
ninety-eight
```
###Output example:
```out
A
```
answer：If there is no answer, please comment
90 or more is a;
B is less than 90 and greater than or equal to 80;
C is less than 80 and greater than or equal to 70;
D is less than 70 and greater than or equal to 60;
Less than 60 is e.
###Input example:
```in
ninety-eight
```
###Output example:
```out
A
```
answer：If there is no answer, please comment