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.Linq;

class ALDS1
{
    static int isprime(int x)
    {
        if (
            x == 2 ||
            x == 3 ||
            x == 5 ||
            x == 7 ||
            x == 11 ||
            x == 13 ||
            x == 17 ||
            x == 19
            ) return 1;
        else if (
            x == 1 ||
            x % 2 == 0 ||
            x % 3 == 0 ||
            x % 5 == 0 ||
            x % 7 == 0 ||
            x % 11 == 0 ||
            x % 13 == 0 ||
            x % 17 == 0 ||
            x % 19 == 0
        ) return 0;
        else if (x < 100000)
        {
            for (int i = 23; i < x; i += 2)
            {
                if (x % i == 0) return 0;
            }
        }
        else if (x >= 100000)
        {
            for (int i = 23; i * i < x; i += 2)
            {
                if (x % i == 0) return 0;
            }
        }
        return 1;
    }
    static void Main()
    {
        int a = int.Parse(Console.ReadLine());
        int b, c=0;
        for (int i = 0; i < a; i++)
        {
            b = int.Parse(Console.ReadLine());
            c += isprime(b);
        }
        Console.WriteLine(c);
    }
}