def is_prime(q):
    q = abs(q)
    if q == 2:
        return True
    if q < 2 or q&1 == 0:
        return False
    return pow(2, q-1, q) == 1

N = int(input())

for i in range(N-100, N+100+1):
    if i == 1:
        continue
    if not is_prime(i):
        print(i)
        break