text: # エラトステネスの篩
  def make_prime_table(n):
      sieve = list(range(n + 1))
      sieve[0] = -1
      sieve[1] = -1
      for i in range(4, n + 1, 2):
          sieve[i] = 2
      for i in range(3, int(n ** 0.5) + 1, 2):
          if sieve[i] != i:
              continue
          for j in range(i * i, n + 1, i * 2):
              if sieve[j] == j:
                  sieve[j] = i
      return sieve
  
  
  X = int(input())
  
  N = 10 ** 6
  prime_table = make_prime_table(N)
  for i in range(X, N + 1):
      if prime_table[i] == i:
          print(i)
          break
  