#include <iostream>

class Primes {
 public:
  int getPrimeCount() const { return prime_count; }
  int getPrime(int i) const { return primes[i]; }
  void addPrime(int i) { primes[prime_count++] = i; }

  bool isDivisibe(int i, int by) { return (i % by) == 0; }

  bool isPrimeDivisible(int candidate) {
    for (int i = 1; i < prime_count; ++i) {
      if (isDivisibe(candidate, primes[i])) return true;
    }
    return false;
  }

 private:
  int prime_count;
  int primes[25000];
};

int main() {
  Primes p;
  int c = 1;
  while (p.getPrimeCount() < 25000) {
    if (!p.isPrimeDivisible(c)) {
      p.addPrime(c);
    }
    c++;
  }
  std::cout << p.getPrime(p.getPrimeCount() - 1) << std::endl;
}