Collecting Numbers

You are given an array that contains each number between $1\dots n1\; \backslash dots\; n$ exactly once. Your task is to collect the numbers from $11$ to $nn$ in increasing order.

On each round, you go through the array from left to right and collect as many numbers as possible. What will be the total number of rounds?

Input

The first line has an integer $nn$: the array size.

The next line has $nn$ integers $x_1,x_2,\dots ,x_{n}x\_1,x\_2,\backslash dots,x\_n$: the numbers in the array.

Output

Print one integer: the number of rounds.