#include <stdio.h>               /* ackermann.c */
#include <stdlib.h>

int ack(int x, int y) {
  if ( x == 0 )
    return y + 1;
  else if ( y == 0 )
    return ack( x - 1 , 1 );
  else
    return ack( x - 1, ack( x, y - 1 ));
}

int main(int argc, char * argv[]) { int i = atoi(argv[1]);
  printf("%d\n", ack(i,i)); return 0; }