# 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
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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 ` `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

 ` 2)  ` `        ``return` `\$x` `- 2;  ` ` `  `    ``return` `\$x` `+ 2;  ` `}  ` ` `  `// Driver code  ` `\$x` `= 5;  ` `echo` `(findY(``\$x``));  ` ` `  `// This code is contributed ` `// by Shivi_Aggarwal ` `?>  `

Output :

```3
```

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