interface number {}

class integer : number {
  public int x;
  public integer(int a) {x=a;}
}
class rational : number {
  public int n, d;  // numerator and denominator
  public rational(int a,int b) { n=a; d=b; }
}
class real : number {
  public double r;
  public real(double a) { r=a; }
}
public class ttt {
  number times(integer A, integer B) => new integer(A.x*B.x);
  number times(integer A, rational B) => new rational(A.x*B.n, B.d);
  number times(integer A, real B) => new real((double)A.x * B.r);
  number times(rational A,rational B) => new rational(A.n*B.n,A.d*B.d);
  number times(rational A,real B) => new real((double)A.n*B.r/(double)A.d);
  number times(real A, real B) => new real(A.r*B.r);
  number times(number A, number B) => times(B,A);

  number product(number[] N) { // find product of an array of numbers
     number ax = new integer(1);
     foreach(var n in N) ax = times(ax,n);
     return ax;
  }

  static bool equals(integer A, integer B) => A.x == B.x;
  static bool equals(integer A, rational B) => A.x*B.d == B.n;
  static bool equals(integer A, real B) => (double)A.x == B.r;
  static bool equals(rational A, rational B) => A.n*B.d == A.d*B.n;
  static bool equals(rational A, real B) => (double)A.n == B.r*(double)A.d;
  static bool equals(real A, real B) => A.r == B.r;
  static bool equals(number A, number B) => equals(B,A);

  public static void Main() {
  }//main
}