A developer is writing a program to validate and classify parcel weights according to a strict specification.

The expected outputs for different inputs are shown in the table below:

The following Python code was written to implement this, but it contains several logic errors and incorrect conditions:

weight_input = input("Enter parcel weight: ")

if weight_input == "":
    print("No classification")
else:
    weight = int(weight_input)
    if weight < 0:
        print("Weight must be positive")
    elif weight >= 1 and weight <= 15:
        print("Lightweight")
    elif weight > 40:
        print("Lightweight")
    elif weight >= 21 or weight <= 29:
        print("Medium")
    elif weight == 20:
        print("Exact Target")
    else:
        print("No classification")