During a heist, thieves plan to replace a cylinder of titanium placed in a weight-sensitive pedestal with a cylinder of iron. The cylinder of titanium has a height of 20 cm and a radius of 5 cm. What is the required volume of the iron cylinder to prevent setting off the alarm? The density of titanium is 4.51 g/cm³ and the density of iron is 7.87 g/cm³.