n = 10 ** 6 + 3 * 10 ** 5
isPrime = [True] * (n + 1)
isPrime[0] = isPrime[1] = False

p = 2
while p * p <= n:
  if isPrime[p]:
    for i in range(p * p, n+1, p):
      isPrime[i] = False
  p += 1

k = int(input())
p = 2
while k > 0:
  if isPrime[p]:
    x = p
    k -= 1
  p += 1
print(x)