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;
namespace std
{
    class Test 
    {
        static void Main(string[] args) {
            var n = Console.ReadLine();
            var num = int.Parse(n);
            int [] input = new int[num]; 
            bool rtn;
            int cnt = 0;

            for( int i = 0; i < num; i++) {
                input[i] = int.Parse(Console.ReadLine());
            }
            Test obj = new Test();
            
           
            for( int i = 0; i < num; i++) {
                rtn = obj.isprime(input[i]);
                if(rtn == true) cnt++;
            }
            Console.WriteLine(cnt);

        }
        public bool isprime(int x) {
        
        
            if (x == 2) return true;
                
            // if x < 2 または x が偶数
            if (x < 2 || x % 2 == 0)  return false;

            int i = 3;
            //  while i <= x の平方根
            while (i <= Math.Sqrt((double)x)) {
            if( x % i == 0)   return false;
            i = i + 2;
            }
            
            return true;
          
        }
    }
}