Problem:
Score: 300 points

Problem Statement

Find the minimum prime number greater than or equal to X.

Notes

A prime number is an integer greater than 1 that cannot be evenly divided by any positive integer except 1 and itself.

For example, 2, 3, and 5 are prime numbers, while 4 and 6 are not.

Constraints

2 \le X \le 10^5

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X

Output

Print the minimum prime number greater than or equal to X.

Sample Input 1

20

Sample Output 1

23

The minimum prime number greater than or equal to 20 is 23.

Sample Input 2

2

Sample Output 2

2

X itself can be a prime number.

Sample Input 3

99992

Sample Output 3

100003

Solution in C (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
int main()
{
  int i, a, num;
  int c = 0;

  scanf("%d", &num);

  for (a = num; a < 100003; a++)
  {c=0;

    for (i = 2; i < a; i++)
    {

      if (a % i == 0)
      {
        c++;
        break;
      }
    }

    if (c == 0)
    {
      break;
    }
  }
  printf("%d", a);
  return 0;
}