sclass BWContrastQuadTree {
  byte min, max;
  
  *() {}
  *(int val) { min = max = (byte) val; }
  *(int min, int max) {
    this.min = (byte) min;
    this.max = (byte) max;
  }
  
  int min() { ret ubyteToInt(min); }
  int max() { ret ubyteToInt(max); }
  
  sclass Composite > BWContrastQuadTree {
    BWContrastQuadTree a, b, c, d;
    
    *() {}
    *(int min, int max, BWContrastQuadTree *a, BWContrastQuadTree *b,
      BWContrastQuadTree *c, BWContrastQuadTree *d) {
      this.min = (byte) min;
      this.max = (byte) max;
    }
  }
}