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)

#include <stdio.h>
#include <math.h>

int isprime(int x){
  if(x==2) return 1;
  if(x<2||x%2==0) return 0;
  int i;
  for(i=3;i<=sqrt(x);i+=2) //????????????????????????????????????
    if(x%i==0)
      return 0;
  return 1;
}

int main(void){
  int n,x,i,num=0;

  scanf("%d",&n);// ??´??°????????°

  for (i = 0;i < n;i++) 
    {
      scanf("%d",&x);
      if(isprime(x))num++;//return 1?????´??????num???????????????
    }
    printf("%d\n",num);
  return 0;
}