# 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 = 4Output: 126Input: n = 16, s = 5Output: 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

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