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 C# (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

namespace ALDS1_1_C
{
	class Program
	{
		static void Main(string[] args)
		{
			int n = int.Parse(Console.ReadLine());
			List<int> vs = new List<int>();

			for(int i = 0; i < n; i++) {
				vs.Add(int.Parse(Console.ReadLine()));
			}

			Console.WriteLine(vs.Count(x => PrimeNumber(x)));
		}

		private static bool PrimeNumber(int number)
		{
			if(number < 2) {
				return false;
			}
			if(number == 2) {
				return true;
			}
			if(number % 2 == 0) {
				return false;
			}

			double s = Math.Sqrt(number);
			for(int i = 3; i <= s; i += 2) {
				if(number % i == 0) {
					return false;
				}
			}

			return true;
		}
	}
}