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 Python (3.4.3) (judge verdict: Accepted)

# ABC149C - Next Prime
def is_prime(n: int) -> bool:
    """
    Evaluate whether a number is prime or not.

    Args:
        n: a number to evaluate

    Returns: whether n is prime or not
    """
    if n == 2:
        return True
    if n == 1 or n % 2 == 0:
        return False
    for i in range(3, int(n ** 0.5) + 1, 2):
        if n % i == 0:
            return False
    return True


def main():
    N = int(input())
    if N != 2 and N % 2 == 0:
        N += 1
    while not is_prime(N):
        N += 2
    print(N)


if __name__ == "__main__":
    main()