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: Accepted)

#!/usr/bin/env ruby

def prime?(x)
  return true if x == 2
  return false if x < 2 || (x % 2).zero?

  i = 3
  while i <= Math.sqrt(x)
    return false if (x % i).zero?
    i += 2
  end
  true
end

n = gets.chomp.to_i

cnt = 0
n.times do
  cnt += 1 if prime?(gets.chomp.to_i)
end

puts cnt