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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <iostream>
using namespace std;
bool isPrime (int);

int main()
{
    int X, i;

    cin>>X;
    for (i=X; !isPrime(i); i++);
    cout<<i;
    return 0;
}

bool isPrime (int a)
{
    int counter=0;
    for (int i=2; i<=a/2; i++)
        if(a%i==0)
            counter++;

    if (counter==0)
        return true;
    else
        return false;
}