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 Julia (1.4.0) (judge verdict: Accepted)

function isprime(n)
    if n <= 1 return false end
    if n == 2 return true end

    for i = 3:2:(n÷2)
        if n % i == 0 return false end
    end

    return true
end

function solve()
    X = parse(Int, readline())

    i = X
    while true
        if isprime(i)
            println(i)
            break
        end
        i+=1
    end
end

solve()