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 9.2.1) (judge verdict: Accepted)

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

int prime(int x){
  int flag=1;
  for(int i=2;i<sqrt(x);i++){
      if(x%i==0) flag=0;
  }
  return flag;
}

int main(void){
  int x,ans;
  scanf("%d", &x);
  
  int j = x;
  while(prime(j)==0) j++;
  /*
  for(int j=x;;j++){
    if(prime(x,j)==1){
  	ans =j;
      break;
    }
  }
  */
  ans = j;
  printf("%d", ans);
  return 0;
}