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 PHP (judge verdict: Accepted)

<?php
$ch=[0,0,1,1];
for($i=4;$i<10000;$i+=2){$ch[]=0;$ch[]=1;}
for($i=3;$i<100;$i+=2) if($ch[$i]) for($j=$i<<1;$j<10000;$j+=$i) $ch[$j]=0;

$l=trim(fgets(STDIN));
$c=0;
for($i=0;$i<$l;$i++){
  $n=trim(fgets(STDIN));
  if($n<10000) $c+=$ch[$n];
  else $c+=isPn($n);
}

echo $c;

function isPn($n){
  if($n<2) return 0;
  if($n==2) return 1;
  if($n%2==0) return 0;
  $max=floor(sqrt($n));
  for($i=3;$i<=$max;$i+=2) if($n%$i==0) return 0;
  return 1;
}
?>