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>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<cstring>
#include<string>
using namespace std;
bool Prime(int x){
	for(int i=2;i*i<=x;i++)if(!(x%i))return 0;
	return 1;
}
int main(){
	int x,i;
	cin>>x;
	for(i=x;!Prime(i);i++);
	cout<<i<<endl;
}