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: Wrong Answer)

import math

input_from = input()
info = input_from.split(' ')
a = int(info[0])

def is_prime(n):
    if n == 2:
        return True
    if n % 2 == 0:
        return False
    for num in range(3, int(math.sqrt(n)), 2):
        if n % num == 0:
            return False
    return True

if a == 2:
    print(2)
else:
    while not is_prime(a):
        a += 1

print("{0}".format(a))