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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include<stdio.h>
void main()
{ 
    long int n;int f=0;int k=0;long int i;
    scanf("%ld",&n);
    while(1)
    { 
        for(i=2;i<=(n+k)/2;i++)
        { 
            if((n+k)%i==0)
            {f=1;
            break;
            }
        }
        if(f==1)
        {k++;f=0;
        continue;}
        else 
        break;
    }
    printf("%ld",n+k);
}