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: Wrong Answer)

#include<stdio.h>
#include<math.h>
long long prime(long long x){
	long long i,len;
	len = sqrt(x);
	for(i=2;i<=len;i++){
		if(x%i==0){
			return 0;
		}
	}
	return 1;
}
int main()
{
	long long N,x;
	scanf("%lld",&N);
	long long i=N;
	do{
		x=prime(N);
		N++;
	}while(x!=1);
	printf("%lld\n",N);
	printf("The minimum prime number greater than or equal to %lld is %lld.\n",i,N-1);
	return 0;
}