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: Time Limit Exceeded)

N = int(input())
over_box = [i for i in range(N,10**6)]
primes = [2]
for i in range(3, N, 2):
    all(i % p != 0 for p in primes) and primes.append(i)
for i in over_box:
    if N ==2:
        print(2)
        break
    elif all(i % p != 0 for p in primes):
        print(i)
        break