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>//解けた
#include<string.h>
int is_prime(int N);
int main(){
    int N;
    printf("数字を入力\n");
    scanf("%d",&N);
    is_prime(N);

}
int is_prime(int N){
    int ct = 0;
    for(int i=1;i<N;i++){
        if(N%i == 0) ct++;
    }
    if(ct == 1){
        printf("%d is prime\n",N);
        return 0;
    }
    else{
    N++;
    is_prime(N);//再帰
    }

    return 0;
}