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 PyPy3 (7.3.0) (judge verdict: Accepted)

X = int(input())

n = 10**6
is_prime = [True] * (n + 1)
is_prime[0] = False
is_prime[1] = False

for i in range(2, int(n**0.5) + 1):
    if not is_prime[i]:
        continue
    for j in range(i * 2, n + 1, i):
        is_prime[j] = False

for i, p in enumerate(is_prime):
    if i >= X and p is True:
        print(i)
        break