int acker(int m,int n) {
  if (m == 0) return n+1;
  if (m > 0) {
    if (n == 0) return acker(m-1,1);
    else
      if (n > 0) return acker(m-1,acker(m,n-1));
  }
}
void main() {
  printf("ackerman(0,0)=%d\n",acker(0,0));
  printf("ackerman(0,9)=%d\n",acker(0,9));
  printf("ackerman(1,8)=%d\n",acker(1,8));
  printf("ackerman(4,2)=%d\n",acker(4,2));
}