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)

def Prime?(n)
	return false if n == 1

	sqrtN = Math.sqrt(n).to_i
	$primelist.each { |p|
		break if p > sqrtN
		return false if n % p == 0
	}

	a = true
	max = $primelist[-1]
	if max < sqrtN
		(max+2).step(sqrtN, 2){ |i|
			isprime = true
			$primelist.each { |p|
				if i % p == 0
					isprime = false
					break
				end
			}
			if isprime
				$primelist << i
				if n % i == 0
					a = false
					break
				end
			end
		}
	end

	return a
end

$primelist = Array.new(0)
$primelist << 2
$primelist << 3

n = 0
gets.to_i.times { n += 1 if Prime?(gets.to_i) }
puts "#{n}"