PROGRAMMING:Count the frequency of letters

Enter a piece of text (end with carriage return) and count the frequency of each letter.
####Input format
>A passage (ending with carriage return)
####Output format
>Statistical results (including times and percentage, and display bar chart, see output example)
####Input sample 1
```in
This is a pen. That is a pencil.
```
####Output sample 1
```out
A: 3 13.0% ***
C: 1 4.3% ****
E: 2 8.7% ****
H: 2 8.7% ****
I: 4 17.4% **
L: 1 4.3% ****
N: 2 8.7% ****
P: 2 8.7% ****
S: 3 13.0% ***
T: 3 13.0% ***
```
####Input sample 2
```in
3 + 4 = 7
```
####Output sample 2
```out
None
```







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