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>

int main(void){

    int X,j,divisor,ans_found = 0;
    long int i;

    scanf("%d",&X);

    i = X;
    while(ans_found == 0){
        divisor = 0;
        for(j = 1;j <= i;j++){
            if(i%j == 0){
                divisor++;
            }
        }
        if(divisor == 2){
            printf("%ld\n",i);
            ans_found = 1;
        }
        i++;
    }

    return 0;
}