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;

class lec01_C{
  public static void Main(){
    int n,x,i,count = 0;
    n = int.Parse(Console.ReadLine());
    for(i =  0;i < n;i++){
      x = int.Parse(Console.ReadLine());
      if(Sosu(x) == true) count++;
    }
    Console.WriteLine(count);
  }
  public static bool Sosu(int x){
    if(x < 2) return false;
    else if(x == 2) return true;
    else if(x % 2 == 0) return false;

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