// help for the implementation from:
// https://www.geeksforgeeks.org/program-to-find-the-nth-prime-number/
// by Ujjwal Kumar Bhardwaj

class NthPrime {
  // function to check if given number is prime or not
  // basic idea is number not divided by any primes are primes
  // bool isPrime(int k) {
  //   // Corner cases
  //   if (k <= 1) return false;
  //   if (k == 2 || k == 3) return true;

  //   // below 5 there are only two prime numbers 2 and 3
  //   if (k % 2 == 0 || k % 3 == 0) return false;

  //   // Using concept of prime number can be represented
  //   // in form of (6*k + 1) or (6*k - 1)
  //   for (int i = 5; i * i <= k; i = i + 6)
  //     if (k % i == 0 || k % (i + 2) == 0) return false;

  //   return true;
  // }

  // int prime(int n) {
  //   if (n == 0) throw new ArgumentError('There is no zeroth prime');
  //   int i = 2;

  //   while (n > 0) {
  //     // each time if a prime number is found decrease n
  //     if (isPrime(i)) n--;

  //     i++; // increase the integer and go ahead
  //   }
  //   i -= 1; // since decrement of k is being done before
  //   // Increment of i, so i should be decreased by 1
  //   return i;
  // }

  bool isPrime(int n) {
    for (int start = 2; start < n; start++) {
      if (n % start == 0) return false;
    }
    return true;
  }

  int prime(int n) {
    if (n == 0) throw new ArgumentError('There is no zeroth prime');

    int counter = 0, number = 2;

    for (; counter < n; number++) {
      if (isPrime(number)) counter++;
    }

    return --number;
  }
}