Missing Number Problem

Given an array containing n distinct numbers from the range \([0, n]\), your task is to find the missing number.

In other words, the array is drawn from the set \(\{0, 1, 2, \dots, n\}\) with exactly one number missing. For example, if the array is [3, 0, 1], then even though the full set should be \(\{0,1,2,3\}\), the missing number is 2.

It is guaranteed that exactly one number in the range \([0,n]\) is missing. Use the formula for the sum of the first \(n\) natural numbers: \(S = \frac{n(n+1)}{2}\) and compare it to the sum of the given array.

inputFormat

The input consists of two lines. The first line contains a single integer n, representing the number of elements in the given array. The second line contains n space-separated integers representing the array elements.

outputFormat

Output a single integer representing the missing number from the array.

## sample

3
3 0 1

2

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