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: Wrong Answer)

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <stdio.h>
#include <cmath>
#include <cctype>
#include <map>

const int INT_INF = 1000000000;                 // 10^9
const long long LONG_INF = 1000000000000000000; // 10^18

using namespace std;

int main()
{
    int x;
    cin >> x;
    if (x % 2 == 0 && x != 2)
    {
        x++;
    }

    while (true)
    {
        bool f = true;
        for (int i = 3; i <= floor(sqrt(x)); i++)
        {
            if (x % i == 0)
            {
                f = false;
                break;
            }
        }
        if (f)
            break;
        cout << x << endl;
        x += 2;
    }

    cout << x << endl;
    return 0;
}