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: Accepted)

#include<stdio.h>
int main(void)
{
  int x,i,j,f;
  scanf("%d",&x);
  if(x==2){
    printf("2\n");
  }else{
  for(i=0;i<=1000;i++){
    f=0;
    for(j=2;j<=x/2+1;j++){
      if((x+i)%j!=0){
        f++;
      }else{
        break;
      }
    }
    /* printf("%d\t",f);*/
    if(f==x/2){
      printf("%d\n",x+i);
      break;
    }
  }
  }
  return 0;
}