You are given an array of n distinct integers, each drawn from the range 0 to n inclusive. Since the range 0..n contains n + 1 values but the array has only n of them, exactly one value from 0..n is absent. Determine the missing value.

The missing value is unique, so the answer is uniquely determined.

Input format

Line 1: an integer n, the number of elements in the array. Line 2: n space-separated distinct integers, each in the range 0..n. If n is such that the line would be empty it will still be present but blank.

Output format

A single integer: the value in 0..n that does not appear in the array.

Constraints

• 1 ≤ n ≤ 100000
• The n array values are distinct and every one lies in [0, n].
• Exactly one value from 0..n is missing.

4
0 1 3 4

2

3
3 1 2

0