// This class computes Greatest Common Divisor using
// Euclid's algorithm.

// The two alternative functions use either recursion
// or iteration.


public class GCD{
  public static final boolean GCD_REC = true;
  public static final boolean GCD_IT = false;

  public static long gcd(long a, long b, boolean method){
    //Check the algorithm condition and perform
    //an eventual swap
    if(a < b){
      long tmp = a;
      a = b;
      b = tmp;
    }

    if(method)
      return gcd_rec(a, b);
    else
      return gcd_it(a, b);
  }

  private static long gcd_rec(long a, long b){
    if(a % b == 0) return b;
    return gcd_rec(b, a % b);
  }

  private static long gcd_it(long a, long b){
    long tmp_a = 1;
    while(a % b != 0){

      tmp_a = a % b;

      a = b;
      b = tmp_a;
    };

    return tmp_a;
  }
}