Problems
MEX
MEX
Do you know how hard it is to pull the trigger?
The famous dictator Lee Xi Seung has an army of 10^5 at his disposal. He numbered them from 0 to 10^5 - 1. The lower the number a person has, the higher his commanding abilities. Then he repressed n of them. Now the dictator is going to conduct a small victorious war with a neighboring state. Therefore, he urgently needs to choose the most talented military who is alive.
Input data
The first line contains the number of repressed n\:(1 \le n < 10^5). The second line contains their numbers in Lee Xi Seung's list — all numbers less than 10^5.
Output data
Print one number — the number of the most talented alive military.
Examples
Input example #1
8 3 0 1 7 2 4 6 17
Output example #1
5