Given an array of integers, The task is to find another integer such that, if all the elements of the array are subtracted individually from the number , then the sum of all the differences should add to 0. If any such integer exists, print the value of , else print .

**Example**

**Input:** arr[] = {1, 2, 3}
**Output:** 2
**Explanation: **
Substracting all the elements of arrays from 2,
The sum of difference is:
1 + 0 + (-1) = 0.

**Solution**: The idea is to calculate the total sum of the array and divide it by the size of the array. If the sum of the array is perfectly divisible by its size then the quotient obtained from this division operation will be the required hidden number.

Below is the implementation of the above idea:

// C# Program to find the

// Hidden Number

using System;

class GFG

{

// Driver Code

public static void Main()

{

// Getting the size of array

int n = 3;

// Getting the array of size n

int []a = { 1, 2, 3 };

// Solution

int i = 0;

// Finding sum of the

// array elements

long sum = 0;

for (i = 0; i < n; i++)
{
sum += a[i];
}
// Dividing sum by size n
long x = sum / n;
// Print x, if found
if (x * n == sum)
Console.WriteLine(x);
else
Console.WriteLine("-1");
}
}
// This code is contributed
// by inder_verma
[tabbyending]

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