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 <string.h>
#include <stdlib.h>
#include <math.h>
#define lop(i, n) for(i=0; i<n; i++)

int main()
{
	int x, i, j, f=0;
	scanf("%d", &x);
	
	for(i=x; i<100200; i++){
		for(j=2; j<=sqrt(x); j++){
			if(i%j==0){
				f=1; break;
			}
		}
		if(f==0){ printf("%d", i); return 0; }
		f=0;
	}
	
return 0;
}