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

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

Print one number — the number of the most talented alive military.

Examples