# Python Program for Number of stopping station problem

There are 12 intermediate stations between two places A and B. Find the number of ways in which a train can be made to stop at 4 of these intermediate stations so that no two stopping stations are consecutive?

Examples –

```Input  : n = 12, s = 4
Output : 126

Input  : n = 16, s = 5
Output : 792
```

 `# Python code to calculate number ` `# of ways of selecting \'p\' non  ` `# consecutive stations out of  ` `# \'n\' stations ` ` `  `def` `stopping_station( p, n): ` `    ``num ``=` `1` `    ``dem ``=` `1` `    ``s ``=` `p ` ` `  `    ``# selecting \'s\' positions ` `    ``# out of \'n-s+1\' ` `    ``while` `p !``=` `1``: ` `        ``dem ``*``=` `p ` `        ``p``-``=``1` `     `  `    ``t ``=` `n ``-` `s ``+` `1` `    ``while` `t !``=` `(n``-``2` `*` `s ``+` `1``): ` `        ``num ``*``=` `t ` `        ``t``-``=``1` `    ``if` `(n ``-` `s ``+` `1``) >``=` `s: ` `        ``return` `int``(num``/``dem) ` `    ``else``: ` `        ``# if conditions does not ` `        ``# satisfy of combinatorics ` `        ``return` `-``1` ` `  `# driver code  ` `num ``=` `stopping_station(``4``, ``12``) ` `if` `num !``=` `-``1``: ` `    ``print``(num) ` `else``: ` `    ``print``(``"Not Possible"``) ` ` `  `# This code is contributed by "Abhishek Sharma 44" `

Output :

```126
```

Please refer complete article on Number of stopping station problem for more details!

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