n = int(input())

def is_prime(n):
    if n <= 1:
        return False
    if n == 2:
        return True
    if n % 2 == 0:
        return False
    max_div = int(n ** 0.5) + 1
    for i in range(3, max_div, 2):
        if n % i == 0:
            return False
    return True

if not is_prime(n):
    print(n)
else:
    start = n - 100
    end = n + 100
    for x in range(start, end + 1):
        if x >= 4 and x % 2 == 0:
            print(x)
            break