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 N_MAX 10000

int isPrime(int x)
{
  int i;
  if (x <= 3) {
    return 1;
  } else if (x % 2 == 0) {
    return 0;
  } else {
    for (i = 3; i <= sqrt(x); i = i + 2) {
      if (x % i == 0) {
        return 0;
      }
    }
    return 1;
  }
}

int main(int argc, char *argv[])
{
  int i, j, n, x;
  int answer = 0;
  scanf("%d", &n);
  for (i = 0; i < n; i++) {
    scanf("%d", &x);
    answer = answer + isPrime(x);
  }
  printf("%d\n", answer);
  return 0;
}