x = 10**6 + 3 * 10**5
is_prime = [True] * (x + 1)
is_prime[0] = is_prime[1] = False
p = 2
while p * p <= x:
  if is_prime[p]:
    for i in range(p*p, x+1, p):
      is_prime[i] = False
  p += 1

k = int(input())
for i in range(x):
  k -= is_prime[i]
  if k == 0:
    print(i)
    break