PROGRAMMING:JMU Python find substring

Input a string, output to get the substring.
###Input format:
-Line 1: input string
-Line 2: enter the starting position of the substring
-Line 3: enter the end position of the substring
###Output format:
Output intercept substring, if the start or end position is illegal, output 'no substring`
###Input example:
```in
python
one
four
```
###Output example:
```out
pyth
```
###Input example:
```in
python
one
ten
```
###Output example:
```out
No strings!
```







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