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;
  bool isprime(int i)
  {  int a,flag=1;
   a=sqrt(i);
   for(int j=2;j<=a;j++)
   {if(i%j==0)
   {  flag=0;
    break;
   }
   }
   return flag;
    
  }
int main()
{  int a;
 cin>>a;
 int i=a;
 while(!isprime(i))
 { 
   i++;
 }
 cout<<i;
}