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: Wrong Answer)

#include <stdio.h>
#include <math.h>
int isPrime(long int a)
{
	int i, sq;
	if (a <= 1)
	{
		return 0;
	}
	sq = sqrt(a);
	for (i = 2; i <= sq; i++)
	{
		if (a % i == 0)
		{
			return 0;
		}
	}
	return 1;
}
int main()
{
	int a, i, p, q;
	scanf("%d", &a);
	p = isPrime(a);
	if (p == 1)
	{
		printf("%d\n", a);
	}
	else
	{
		for (i = 1; i <= a; i++)
		{
			a = a + i;
			p = isPrime(a);
			if (p == 1)
			{
				printf("%d\n", a);
				break;
			}
		}
	}
	return 0;
}