short median (short x1, short x2, short x3)
{	
  short mid;
  mid = x3;
  if (x2 < x3)
    if (x1 < x2)
      mid = x2;
    else {
      if (x1 < x2)  // x2 au lieu de x3
        mid = x1;   // non--feasible
    }
  else
    if (x1 > x2)
      mid = x2;
    else if (x1 > x3) 
      mid = x1;     
  return mid;
}