We have $N$ bricks arranged in a row from left to right. The $i$\-th brick from the left $(1 \leq i \leq N)$ has an integer $a_i$ written on it. Among them, you can break at most $N-1$ bricks of your choice. Let us say there are $K$ bricks remaining. Snuke will be satisfied if, for each integer $i$ $(1 \leq i \leq K)$, the $i$\-th of those brick from the left has the integer $i$ written on it. Find the minimum number of bricks you need to break to satisfy Snuke's desire. If his desire is unsatisfiable, print `-1` instead.

Input is given from Standard Input in the following format: >$N$\ >$a_1$ $a_2$ $...$ $a_N$ #### Constraints - All values in input are integers. - $1 \leq N \leq 200000$ - $1 \leq a_i \leq N$

Print the minimum number of bricks that need to be broken to satisfy Snuke's desire, or print `-1` if his desire is unsatisfiable.

***For Sample #1:*** If we break the leftmost brick, the remaining bricks have integers $1$ and $2$ written on them from left to right, in which case Snuke will be satisfied. ***For Sample #2:*** In this case, there is no way to break some of the bricks to satisfy Snuke's desire. ***For Sample #4:*** There may be no need to break the bricks at all.

AtCoder [ABC148D]