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;
public class Eratosthenes
{
	public static void Main(string[] args)
	{
		int count = int.Parse(Console.ReadLine());
		int sum = 0;//?´???°???????¨?
		
		for (int i = 0; i < count; i++)
		{
			//?????????????±????????????????
			int target = int.Parse(Console.ReadLine());
			//????????????
			//2???????°??????£???????????§??????????????????if?????????????????\????????????
			if(target==2)
			{
				sum++;
			}
			if ((target >= 2) && ((target % 2) != 0)) 
			{
				
				int j = 3;
				do{
					
					
					if ( target == 3||target==5||target==7)
					{//?´???°??§??????
						sum ++;
						break;
					}
					
					if (target % j == 0)
					{//?´???°??§?????????
						break;
					}
					if ((j + 2) >( target / (j+2)))
					{
						//????????????????????§????????????break?????????????????´????????????????????\???
						sum ++;
						break;
					}
					
					j+=2;
				}while(j<=target/j);
			}
			
		}
		
		Console.WriteLine(sum);
	}
}