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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;
using System.Threading;

class Program
{
    bool isPrime(int num)
    {
        for (int i = 2; i * i <= num; i++)
        {
            if(num % i == 0) return false;
        }
        return true;
    }

    static void Main() => new Program().Solve();
    void Solve()
    {
        int N = int.Parse(Console.ReadLine());
        for (int i = N; ; i++)
        {
            if (isPrime(i))
            {
                Console.WriteLine(i);
                return;
            }
        }
    }
}