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++ (Clang 10.0.0) (judge verdict: Wrong Answer)

#include <iostream>
using namespace std;
int main(void){
    int X;
    cin >> X;
    int ans = X;
    bool is_prime = false;
    while(!is_prime){
        ans++;
        is_prime = true;
        for(int i=2;i*i <= ans;i+=2){
            if(ans % i == 0){
                is_prime = false;
                break;
            }
            if(i == 2)i--;
        }
    }
    cout << ans << endl;
}