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)

# import sys
# sys.setrecursionlimit(10 ** 6)
# # input = sys.stdin.readline    ####
# def int1(x): return int(x) - 1
def II(): return int(input())

# def MI(): return map(int, input().split())
# def MI1(): return map(int1, input().split())
#
# def LI(): return list(map(int, input().split()))
# def LI1(): return list(map(int1, input().split()))
# def LLI(rows_number): return [LI() for _ in range(rows_number)]
#
# def SI(): return input().split()
#
# def printlist(lst, k='\n'): print(k.join(list(map(str, lst))))
# INF = float('inf')
#
# from math import ceil, floor, log2, sqrt
# from collections import deque
# from itertools import combinations as comb, combinations_with_replacement as comb_w, accumulate, product
# from heapq import heapify, heappop, heappush

def is_prime(n):
    for i in range(2, int(pow(n, 0.5))+1):
        if n % i == 0:
            return False

    return True


def solve():
    X = II()

    while 1:
        if is_prime(X):
            print(X)
            return

        X += 1



if __name__ == '__main__':
    solve()