def sieve_of_eratosthenes(ub):
    # O(n loglog n) implementation.
    # returns prime numbers <= ub.
    if ub < 2:
        return []
    prime = [True]*(ub+1)
    prime[0] = False
    prime[1] = False
    p = 2
    while p*p <= ub:
        if prime[p]:
            # don't need to check 2p ~ (p-1)p (they've already been checked).
            for i in range(p*p, ub+1, p):
                prime[i] = False
        p += 1
    return [i for i in range(ub+1) if prime[i]]

N = int(input())
primes = sieve_of_eratosthenes(N + 100)
for i in range(max(N-100, 2), N+101):
    if i not in primes:
        print(i)
        break