Problem:
Prime Numbers

A prime number is a natural number which has exactly two distinct natural number divisors: 1 and itself. For example, the first four prime numbers are: 2, 3, 5 and 7.

Write a program which reads a list of N integers and prints the number of prime numbers in the list.

Input

The first line contains an integer N, the number of elements in the list.

N numbers are given in the following lines.

Output

Print the number of prime numbers in the given list.

Constraints

1 ≤ N ≤ 10000

2 ≤ an element of the list ≤ 108

Sample Input 1

5
2
3
4
5
6

Sample Output 1

3

Sample Input 2

11
7
8
9
10
11
12
13
14
15
16
17

Sample Output 2

4

Solution in Ruby (judge verdict: Wrong Answer)

Fixnum.class_eval {
  def is_prime?
    return true if self == 2
    return false if self < 2 or self % 2 == 0

    3.step(Math.sqrt(self).ceil, 2) { |i|
      return false if self % i == 0
    }
    true
  end
}

STDIN.read.split("\s")[1..-1].map(&:to_i).map(&:is_prime?).select { |x| x }.size