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 Python (3.4.3) (judge verdict: Accepted)

x = int(input())

if x==2:
    print(2)
elif x==3:
    print(3)
else:
    while True:
        if x%2==0 or x%3==0:
            x += 1
            continue
        else:
            tmp = 0
            divisor_lst = [1, x]
            for i in range(1,x+1):
                if x%i==0 and i not in divisor_lst:
                    tmp = 1
                    x += 1
                    break
            if tmp==0:
                break
            elif tmp==1:
                continue
    print(x)