bmi calculation formula imperial and metric

def introduction_page():
  print("Welcome to the BMI Calculator")
  to_start = str(input("Y to start. N to exit"))
  if to_start in ("Y","y"):
    print("We will calculate now")
    return main_page()
  else:
    print("exiting")


def main_page():
  found = False

  while not found:
    weight_store = float()
    height_store = float()
    user_weight = float(input("Please enter your weight(kg): "))
    weight_confirm =  str(input("Y to confirm. N to re-enter"))
    if weight_confirm in("y","Y"):
      weight_store = weight_store + user_weight
      while not found:
        user_height = float(input("Please enter your height(m): "))
        height_confirm = str(input("Y to confirm. N to re-enter"))
        if height_confirm in ("Y","y"):
          height_store = height_store + user_height
          total_height = (height_store * height_store)
          total_weight = (weight_store)
          BMI = (total_weight / total_height)
          print (int(BMI))
          if (BMI < 18.5 or BMI <25) :
            print("Normal Weight")
            found = True
          elif (BMI < 25 or BMI < 30):
            print("Over-weight")
            found = True
          elif (BMI < 30 or BMI < 40):
            print("Obesity")
            found = True
          else:
            print("Morbid Obesity")
            found = True
        else:
          print("Please re-enter")
    else:
      print("Please re-enter!")


introduction_page()