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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
Author Олег Петров
Source Летняя школа Севастополь 2013, Волна 1, День 3