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 sys
input=sys.stdin.readline
import math
X = int(input())
if X == 2:
    print(2)
x = math.ceil(math.sqrt(X))
for i in range(X,X+1000):
    c = 0
    for j in range(2,x+1):
        if i % j == 0:
            c = 1
            break
    if c == 0:
        print(i)
        break