There is a class of $N$ students. Each student has a unique class number from $1$ to $N$.

The Biology teacher Mr. So is now handing out exam papers in ascending order of class number ($1$ to $N$). The class lines up to take the exam papers in order. However, since some students forgot their class number, they are in the wrong position in line. So, some students receive someone else's exam paper.

Count the number of students who receive the wrong exam paper.

Input

The first line contains an integer $N$ ($1 \le N \le 50$).
The second line contains $N$ integers, the class numbers of each student in line. The first integer is the class number of the first student in line, the second integer is the class number of the second student, etc.

Output

Output the number of students who receive the wrong exam paper.