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<bits/stdc++.h>
using namespace std;
#define ll long long int
#define pb emplace_back
#define mp make_pair
#define f(i,a,n) for(int i=a ; i<n ; i++)
#define F first
#define E endl
#define S second
#define fast ios:: sync_with_stdio(false),cin.tie(0);
     
     
bool isprime(ll n)
{
	if(n==1 || (n!=2 && n%2==0))
	return false; 
	if(n==2)
	return true; 
	for(ll i=3;i<=sqrt(n);i+=2)
	if(n%i==0)
	return false; 
	return true; 
}   
int main()
{
	ll x;
	cin>>x;
	for(ll i=x;i<=1e5+10;i++)
	{
		if(isprime(i)==true)
		{
		  cout<<i;
		  break;
		}
	}
}