#include <stdio.h>
#define MAX 4 /* 42 second */
struct ss {
  int val;
  struct ss *next;
};
typedef struct ss s_node;
typedef s_node *link;
link stack=NULL;

int stacksize() {
  link top;
  int i;

  top=stack; i=0;
  while (top != NULL) { i++; top=top->next; }
  return i;
}

void push(int k) {
  link kk;
  kk=(link)malloc(sizeof(s_node));
  kk->next=stack; kk->val=k; stack=kk;
}

void pop(int *k) {
  link top;

  if (stack != NULL) {
    *k=stack->val; top=stack; stack=stack->next; free(top);
  }
}

void main() {
  int n,m,ans,k1,k2,kk;

  clrscr();
 printf("give me ackerman 1st and 2nd parameter --> "); scanf("%d %d",&m,&n);
  if ((m < 0) || (n < 0)) printf("cannot compute ackerman!!!\n");
  else {  /* m>=0 && n>=0 */
    push(m); push(n); k1=m; k2=n;
    while ((kk=stacksize()) != 1) {
      pop(&n); pop(&m);
/*      printf("m=%d n=%d\n",m,n); getche(); */
      if (m == 0) push(n+1);
      else
	if (n == 0) {
	  push(m-1); push(1);
	}
	else {
	  push(m-1); push(m); push(n-1);
	}
    } /* while */
    pop(&ans); printf("ackerman(%d,%d)=%d\n",k1,k2,ans); getche();
  }
}