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<math.h>

int main(void){
  int n;
  scanf("%d",&n);
  
  int t = n , flag = 0;

  while(flag == 0){
    for(int i = 2;i <= sqrt(t);i ++){
      if(t%i == 0){
        flag = 1;
      }
    }
    if(flag == 1){
      flag = 0;
      t ++;
    }
    else{
      flag = 1;
    }
  }

  printf("%d\n",t);

  return 0;
}