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 5.4.1) (judge verdict: Accepted)

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

int main(void)
{
	int x;
	int i;
	int limit;
	int j;
	int flag=0;
	int ans=0;
	
	scanf("%d",&x);
	
	while(ans==0){
		limit = (int)sqrt((double)x);
		for(j=limit;j>1;j--)
			if(x%j==0)
				break;
		if(j==1)
			ans=x;
		x++;
	}
	
	printf("%d",ans);
	return 0;
}