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>
typedef long long int ll;
#define vaibhavv06               \
	ios::sync_with_stdio(false); \
	cin.tie(NULL);               \
	cout.tie(0);
#define int long long
#define MM(a,b) memset(a,b,sizeof(a))
const ll MOD = 1000000007;
using namespace std;

bool check(int n){
	for(int i=2;i*i<=n;i++){
		if(n%i==0) return false;
	}
	return true;
}

int32_t main(){
    vaibhavv06;
	int n; cin>>n;
	n--;
	while(!check(++n));
	cout<<n<<endl;
}