A roster assigns badge ids 0, 1, 2, ..., n (that is n + 1 distinct ids). A scanner then reads n of them exactly once each, so exactly one id from the full set is missing. Given the n scanned ids in some arbitrary order, determine the single missing id.
Input format
Line 1: an integer n.
Line 2: n space-separated distinct integers, each in the range 0..n, the scanned ids.
Output format
A single integer: the one id in 0..n that was not scanned.
Constraints
- 1 <= n <= 100000
- The scanned ids are
ndistinct values, each between 0 and n inclusive.