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>

#define true  1
#define false 0

int isprime(int n) {
  // special condition
  if (2 == n) return true;
  for (int i = 2; i <= sqrt(n); i++) {
    if (0 == n % i) return false;
  }
  return true;
}

int main(int argc, char **argv) {
  int n, a, cmt = 0;

  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &a);
    if (isprime(a)) cmt++;
  }

  printf("%d\n", cmt);
  return 0;
}