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;

class Program {
    static string ReadLine() { return Console.ReadLine().Trim(); }
    static int ReadInt() { return int.Parse(Console.ReadLine()); }
    static int[] ReadInts() { return ReadLine().Split().Select(int.Parse).ToArray(); }
    static string[] ReadStrings() { return ReadLine().Split(); }

    static bool IsPrime(int n) {
        if (n == 2) return true;
        if (n % 2 == 0) return false;

        for (int i = 3; i * i <= n; i += 2) {
            if (n % i == 0) {
                return false;
            }
        }
        return true;
    }

    static void Main() {
        int ans = 0;
        int n = ReadInt();
        for (int i = 0; i < n; i++) {
            int x = ReadInt();
            if (IsPrime(x)) {
                ans++;
            }
        }
        Console.WriteLine(ans);
    }
}