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package ackerman;

/**
 *
 * @author suchenek
 */
/*
This is a well tested program that computes one value of 3-argument Ackerman's function.
1st and 2nd argument are the numbers on which a two-argument operation is to be carried out.
3rd argument is an index of the operation.
E.g.,   A(k, m, 0) = k + m
	A(k, m, 1) = k * m
	A(k, m, 2) = k ^ m
etc.
*/

 public class Ackerman3arg
 {
 static long count = 0;

 	public static void main (String [] args)
 	{
//  		int n = Integer.parseInt(args[0]);
//  		int m = Integer.parseInt(args[1]);
//		int k = Integer.parseInt(args[2]);
                long n = 2;
                long m = 2; //second arg of "the" Ackermann's function
                long k = 3; //first arg of "the" Ackermann's function
  			long a = A(2,m + 2, k - 1) - 3;
 			System.out.print("A(" + n + ", " + m + ", " + k + ") = " +  a);
 			System.out.println(" count = " +  count);

	}

	public static long A(long k, long m, long n)
	{
// 		count++;
 		if (n == 0) return m + k;
 		else
 		{
	 		if (m == 0)
	 		{
	 			if (n == 1) return 0;
	 			else
                                {
                                     if (n == 2) return 1;
                                     else return k;
                                }
	 		}

	 		else return A(k, A(k, m-1, n), n-1);
	 	}
 	}
 }

/*
A(k, m, 0) = m + k;
A(k, 0, 1) = 0
A(k, 0, 2) = 1
A(k, 0, n+3) = k
A(k, m+1, n+1) = A(k, A(k, m, n+1), n)
*/
 
 /* 
Note: "the" Ackermann function (with a simpler recurrence relation) refers to:
A(2, n+2, m-1) - 3
*/