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;
 
int main() {
  int X;
  cin>>X;
  int N[100010];
  N[1]=0;
  N[2]=1;
  for (int i=3;i<100010;i++){
    N[i]=1;
  }
  
  for (int i=2;i<100010;i++){
    for(int j=2;j<i;j++){
      if(i%j==0){
        N[i]=0;
        break;
      }
    }
  }
  
  for (int i=X;i<100010;i++){
    if(N[i]==1){
      cout<<i<<endl;
      return 0;
    }
  }
  
    cout<<"Error"<<endl;
    return 0;  
}