Given a number x , find y such that x*y + 1 is not a prime

Given a number x, Find y (y > 0) such that x*y + 1 is not a prime.**Examples:**

Input : 2 Output : 4 Input : 5 Output : 3

Observation:

x*(x-2) + 1 = (x-1)^2 which is not a prime.

Approach :

For x > 2, y will be x-2 otherwise y will be x+2

## C++

`#include <bits/stdc++.h>` `using` `namespace` `std;` `int` `findY(` `int` `x)` `{` ` ` `if` `(x > 2)` ` ` `return` `x - 2;` ` ` `return` `x + 2;` `}` `// Driver code` `int` `main()` `{` ` ` `int` `x = 5;` ` ` `cout << findY(x);` ` ` `return` `0;` `}` |

## Java

`// JAVA implementation of above approach` `import` `java.util.*;` `class` `GFG` `{` ` ` `public` `static` `int` `findY(` `int` `x)` ` ` `{` ` ` `if` `(x > ` `2` `)` ` ` `return` `x - ` `2` `;` ` ` ` ` `return` `x + ` `2` `;` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `main(String [] args)` ` ` `{` ` ` `int` `x = ` `5` `;` ` ` `System.out.println(findY(x));` ` ` `}` ` ` `}` `// This code is contributed` `// by ihritik` |

## Python3

`# Python3 implementation of above` `# approach` `def` `findY(x):` ` ` `if` `(x > ` `2` `):` ` ` `return` `x ` `-` `2` ` ` ` ` `return` `x ` `+` `2` `# Driver code` `if` `__name__` `=` `=` `'__main__'` `:` ` ` `x ` `=` `5` ` ` `print` `(findY(x))` `# This code is contributed` `# by ihritik` |

## C#

`// C# implementation of above approach` `using` `System;` `class` `GFG` `{` `public` `static` `int` `findY(` `int` `x)` `{` ` ` `if` `(x > 2)` ` ` `return` `x - 2;` ` ` `return` `x + 2;` `}` `// Driver code` `public` `static` `void` `Main()` `{` ` ` `int` `x = 5;` ` ` `Console.WriteLine(findY(x));` `}` `}` `// This code is contributed` `// by Subhadeep` |

## PHP

`<?php` `// PHP implementation of above approach` `function` `findY(` `$x` `)` `{` ` ` `if` `(` `$x` `> 2)` ` ` `return` `$x` `- 2;` ` ` `return` `$x` `+ 2;` `}` `// Driver code` `$x` `= 5;` `echo` `(findY(` `$x` `));` `// This code is contributed` `// by Shivi_Aggarwal` `?>` |

## Javascript

`<script>` `// JavaScript implementation of above approach` `// Function to check whether it is possible` `// or not to move from (0, 0) to (x, y)` `// in exactly n steps` `function` `findY(x)` `{` ` ` `if` `(x > 2)` ` ` `return` `x - 2;` ` ` `return` `x + 2;` `}` `// Driver code` `var` `x = 5;` `document.write(findY(x));` `// This code is contributed by Ankita saini` `</script>` |

**Output:**

3

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