1051.py

salary = float(input())

if (salary > 0 and salary <= 2000.00):
    print("Isento")

elif (salary > 2000.00 and salary <= 3000.00):
    amount = salary - 2000.00
    tax = amount * 8/100
    print("R$ %.2f" % (tax))

elif (salary > 3000.00 and salary <= 4500.00):
    amount = salary - 3000.00
    tax = (1000 * 8/100) + (amount * 18/100)
    print("R$ %.2f" % (tax))

elif (salary > 4500.00):
    amount = salary - 4500.00
    tax = (1000 * 8/100) + (1500 * 18/100) + (amount * 28/100)
    print("R$ %.2f" % (tax))