# Number of ways in which N can be represented as the sum of two positive integers

Given a number **N**, the task is to find the number of unique ways in which **N** can be represented as a sum of two positive integers.**Examples:**

Input:N = 7Output:3

(1 + 6), (2 + 5) and (3 + 4).Input:N = 200Output:100

**Approach:** The number of ways in which the number can be expressed as the sum of two positive integers are **1 + (N – 1), 2 + (N – 2), …, (N – 1) + 1** and **(N – 2) + 2**. There are **N – 1** terms in the series and they appear in identical pairs i.e. **(X + Y, Y + X)**. So the required count will be **N / 2**.

Below is the implementation of the above approach:

## C++

`// C++ implementation of the approach` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to return the number of` `// distinct ways to represent n` `// as the sum of two integers` `int` `ways(` `int` `n)` `{` ` ` `return` `n / 2;` `}` `// Driver code` `int` `main()` `{` ` ` `int` `n = 2;` ` ` `cout << ways(n);` ` ` `return` `0;` `}` |

## Java

`// Java implementation of the approach` `class` `GFG` `{` ` ` ` ` `// Function to return the number of` ` ` `// distinct ways to represent n` ` ` `// as the sum of two integers` ` ` `static` `int` `ways(` `int` `n)` ` ` `{` ` ` `return` `n / ` `2` `;` ` ` `}` ` ` ` ` `// Driver code` ` ` `public` `static` `void` `main(String args[])` ` ` `{` ` ` `int` `n = ` `2` `;` ` ` ` ` `System.out.println(ways(n));` ` ` `}` `}` `// This code is contributed by AnkitRai01` |

## Python3

`# Python3 implementation of the approach` `# Function to return the number of` `# distinct ways to represent n` `# as the sum of two integers` `def` `ways(n):` ` ` `return` `n ` `/` `/` `2` `# Driver code` `n ` `=` `2` `print` `(ways(n))` `# This code is contributed by Mohit Kumar` |

## C#

`// C# implementation of the approach` `using` `System;` `class` `GFG` `{` ` ` `// Function to return the number of` `// distinct ways to represent n` `// as the sum of two integers` `static` `int` `ways(` `int` `n)` `{` ` ` `return` `n / 2;` `}` `// Driver code` `public` `static` `void` `Main()` `{` ` ` `int` `n = 2;` ` ` `Console.WriteLine(ways(n));` `}` `}` `// This code is contributed by Nidhi_Biet` |

## Javascript

`<script>` `// Javascript implementation of the approach` `// Function to return the number of` `// distinct ways to represent n` `// as the sum of two integers` `function` `ways(n)` `{` ` ` `return` `parseInt(n / 2);` `}` `// Driver code` `var` `n = 2;` `document.write(ways(n));` `// This code is contributed by noob2000.` `</script>` |

**Output:**

1

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