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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<iostream>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>
#include<iomanip>
#include<bitset>
using ll=long long;


int main(){
  int x;
  cin >> x;
  bool f=true;
  do{
    int cnt=0;
    for(int i=1;i<=x;i++){
      if(x%i==0)cnt++;
    }
    if(cnt==2)f=false;
    else x++;
  }while(f);

  cout << x;
}