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 <iostream>
using namespace std;
int main() {
  int X;
  int flg;
  cin >> X;
  while(true){
    flg = 0;
    for(int j=2;j<=X/2;j++){
      if(X%j == 0){
        flg = 1;
        break;
      }
    }
    if(flg == 0){
        break;
    }
    X++;
  }
  cout << X;
}