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<stdio.h>
#include<math.h>
#include<stdlib.h>

int main()
{
    int x,i,red;
    float num;

    scanf("%d",&x);

    while(1)
    {
        if(x==2)
            break;
        else
        {
            red = 0;
        num = ceil(sqrt(x));

        for(i=2;i<=num;i++)
        {
            if(x%i==0)
            {
                red++;
                break;
            }
        }

        if(red!=0)
            x++;
        else
            break;
        }
    }

    printf("%d",x);

    return 0;
}